The game can be pretty good fun; when you're actually allowed to play it, that is.
~
Pros:
+ Controllable Camera & Improved Aiming: Technically this was introduced in MGS3: Subsistence, but seeing as I never got round to buying it, I'll mention it here instead: the ability to control the camera yourself is a great relief, allowing you to scout ahead and admire the scenery with much greater ease. It also frees up your aiming a great deal, and the ability to controllably move and fire (including 1st-Person mode) does the game no end of good.
+ OctoCamo: Effectively solving the fiddly annoyance of the MGS3 camouflage system, the OctoCamo is a great way of blending in without disrupting gameplay. I think it could have been better, however, if the 'visible' time between changing patterns lasted a bit longer, forcing players to plan ahead a little more (this is offset by the camo seemingly being less effective than that of MGS3, though).
+ Voice Acting: The actors must surely have had their doubts about the script, so the fact they managed to suppress their laughter/boredom/bemusement long enough to deliver strong, convincing performances is worthy of commendation! You also have to wonder how much water David Hayter had to chug to recover from Snake's ludicrously gruff voice...
+ Warzone Setting: Like its predecessor, MGS4 transplants the stealth gameplay into an interesting new setting: in this case, sneaking straight through a warzone. Since you're technically on neither army's side, it's something I haven't really seen in another game, and gives MGS4 a unique feel and approach.
+ Expansive Environments: Most of the areas cover quite a lot of ground, with multiple routes available to take, and the variety you'll find within is commendable.
+ Cinema/Gameplay Fusion: While most of the time the divide between cinematics and gameplay is quite jarring, there are moments when you finally get to see the two genuinely fused together; and when it happens, you'll finally see what this game had the potential to be. In particular, the brief split-screen moments are very well done, and genuinely involve you in what's going on (until the game inevitably takes your control away again, that is).
+ In-Game Codec: The fact that you can now recieve essential advice without having to pause the game is a long-overdue feature, and one you'll be thankful for in terms of flow and immersion.
+ Longveity: With such a wide variety of routes and approaches to take, not to mention the secret items and rankings you can acquire, there's plenty to do should you ever return to the game.
Cons:
- Story & Plot: MGS2 burdened this game with the task of explaining one of the most needlessly complex, stupid plots in gaming history, and in that respect, it doesn't actually do too bad a job. However, in transplanting the setting to a radically different future, the game loses both its convincing black-ops air and its relevance to our current times - while you can pull out the occasional message or two if you use your imagination, the game very rarely gives any true thoughts or debates on any subject but its own melodramatic storyline. Also, the plot (which doesn't actually develop as much as you'd expect) doesn't really have any truly interesting twists like the previous games did, and when there are any, they either have very little dramatic impact, are incredibly obvious so you're left waiting for the characters to catch up with what you realized hours ago, or are so utterly far-fetched that you wish they hadn't bothered (to be fair, the game is trying desperately to clean up the mess of MGS2, so there isn't really room for many more twists).
- Characterisation: Not much characterisation actually takes place throughout the game, and whenever there is any, it's so exaggerated, or forced out of the blue, or repetitive from past games in the series, that you'll quickly grow pretty sick of them all. The only character who consistently remains tolerable is Snake himself (largely because he doesn't actually say very much compared to usual), but even here they missed the opportunity to develop his personality and emotions in light of his sudden ageing: instead of genuinely seeing what his decaying body is doing to his mind and outlook, all we get is him continuously coughing, smoking, and talking vaguely about his duty. You'll also grow sick of how absolutely every character knows every last detail about the plots of each Metal Gear game, but somehow Snake manages to stay out of the loop!
- Cinematics & Dialogue: Of course you expect them from a Metal Gear game, but even so, the sheer amount of cut-scenes in MGS4 is simply unnacceptable - you will literally spend at least half of the game, probably more, just watching the damn thing. There are so many scenes that could have been vastly improved by letting the player actually take part somehow, and given how well it works when these cinema/gameplay fusions actually happen, it's a bitter disappointment to keep seeing potentially great set-pieces pass by without your involvement. I suspect the reason for this is that Hideo Kojima is desperately in love with himself and his cinematics, to the point where he doesn't want even the player interfering with his vision, and refuses to let anyone edit them down at all. This is bad enough with his fairly average directing (he's very given to repetition, plagarism and absurd exaggeration), but what really makes the cinematics unendurable is the dialogue. There is no way around this for even the most loyal of fans: the man simply cannot write to save his life. The precious few moments set aside for characterisation are botched terribly with pretentious metaphors and complete lack of subtlety, and fatally for a script so obsessed with plot exposition, it takes an incredible amount of time to reveal even the smallest development (which must be part of the reason why the plot doesn't actually develop too far). The key offender here is repetition: Kojima finds an incredible amount of ways to say the exact same things at least three times over, and yet can't avoid repeating key words dozens of times within the space of minutes (if you remove the words 'nano-mahcines', 'Patriots', 'proxy', 'system', and several other key offenders, the script would be half as long)!
- Limited Codec: Unlike its predecessors (and unusually for a game just waiting to drown you in dialogue), the Codec features very few people to talk to, and those there are don't have nearly as much to say as before: this would have been the perfect means of siphoning off details and backstory into an optional pursuit for those who cared enough, but as it is, the Codec almost entirely loses its purpose. Even the Codec in MGS for the GameBoy Colour had far more to say!
- Drebin's Shop & Excessive Inventory: Any kind of challenge or enjoyable exploration regarding ammo-conservation and weapon-acquisition is completely removed by Drebin's Shop, basically allowing the player to be a walking arsenal from the very start. Compounding this, there are such an absurd amount of weapons and items that none of them feel particularly distinct or special (which the lack of Codec information only makes worse), and you will almost certainly never need to use the vast majority of them, even on harder difficulties. Also, with so many weapons and limitless ammo available, CQC has such a reduced role in the game that you can quite easily never use it at all, which is a shame after its great implementation in MGS3.
- Excessive Globe-trotting: The game jumps about between quite a few wildly different settings, which is all well and good; except when you add in the sheer amount of cut-scenes you'll be forced to watch in each of them, this means you'll barely have the chance to settle into your new surroundings before you're already moving on, missing all sorts of gameplay opportunities in all of them. This only gets worse as the game goes on, as the cut-scene-to-gameplay ratio shifts dramatically to the point where you barely have any involvement whatsoever - to have one consistent yet varied setting, as in MGS1 and 3, would have been preferrable.
- Limited Warzone Options: While the Warzone setting is nice, and certainly has its moments, it's not quite as fully-fleshed as it could be. There's no emotional reason to be sympathetic to one side over another (even the dialogue admits this!), you can only gain anything by siding with the rebels (who I think are a little too easy to win-over), there are no real developments in the conflicts unless you step in yourself, there are rarely long-term consequences or rewards for winning a battle, and it's impossible to tell beforehand which fights can actually be conclusively won or not. Still, a nice idea!
- Excessive Crawling & Obvious Hiding: Because it's by far the most effective way of staying hidden, you'll spend almost all of the game crawling on the floor, which can be a bit slow and repetitive: there should have been some sort of drawback or incentive to make the player mix it up a bit. Another problem with the stealth in the game is that you almost never have to utilise the 'classic' approach of keeping yourself hidden behind objects, which was fundamentally much more tense and challenging than just lying still in the open.
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It must seem like a massive list of complaints I've given, but in truth, it almost all centres around the story and cinematics. The gameplay itself is certainly among the best the series has to offer, but you're given such a frustratingly short amount of time to actually play it in that it never really gets to develop and draw you in like its predecessors did. The fact is, if Kojima had put half as much effort into the gameplay as he did with his cinematics (not to mention drastically cut the amount and length of them), then MGS4 would have been a far better experience overall: as it is, I don't think time will be as favourable to MGS4 as its reviews have been.