The first Metal Gear Solid game that doesn't overcome its flaws.
PROS
The story is the strongest part of Portable Ops, as it's solid (no pun intended) for the most part. There are moments here and there that don't quite work, but by and large, the story is interesting. It fills in the timeline rather well, at least with regards to Big Boss/Naked Snake.
In terms of length, Portable Ops runs around 15 hours or so, which is a good length for a PSP game, as well as the average length of games in the Metal Gear series as a whole.
As usual with the Metal Gear series, the actor playing Snake (David Hayter) is good. Likewise, the music in the game is excellent, also a norm for the series.
CONS
The biggest problem with Portable Ops is easily the cutscenes. What's wrong with them? Well, put simply, they aren't real cutscenes. Rather, they are what amounts to voiced-over black-and-white storyboards. The only similar thing I've seen to this sort of thing is in the X-Men 3 movie game. It's lame, and a cheap cop-out designed to save money. At least with X-Men there was a "this is a comic book" slant to it that sort of made it acceptable (sort of, but not really), but that doesn't work here. Here, it's just lame. There's simply no excuse for it.
Likewise, the fact that there is no voice acting outside of the cutscenes (aside from some lame voice acting by enemy soldiers whenever you're spotted: "HQ?" "This is HQ." "We've spotted the enemy. Commence alert formation!" "Acknowledged. The enemy is nearby." ... who talks like this?) is simply unacceptable, considering the game came out in 2006. One might try to argue that this was done due to the PSP having memory issues that wouldn't allow full voice acting, but that's a fallacy: a UMD disc can hold 1.8 gigs of memory - which is more than a Gamecube disc can hold. And plenty of Gamecube games feature full voice acting.
The acting in Portable Ops is almost uniformly bad. Apart from Snake and a couple other characters who acquit themselves well, the acting is downright awful. This might partly be due to whoever was writing the dialogue: it's so horrendous that at times it's cringe-inducing. It's rivals the dialogue of someone like George Lucas in the pantheon of bad writing.
Then there are the gameplay issues. For one thing, Portable Ops is very frustrating. Secondary characters (those you control outside of Snake) die very easily. Part of this is because of inconsistent AI. If you are wearing the type of uniform that any given AI character is wearing, they aren't supposed to recognize you as an enemy unless you do something suspicious. Yet there were many times where I merely walked by a similarly-clothed enemy and the alert was raised. At other times I would kill an enemy within plain sight of another, and the second one would completely ignore me. It's just bad programming, which isn't a good thing considering this is supposed to be a stealth game.
The controls don't translate well from consoles onto PSP. In fact, they're downright bad. Moving your character is awkward at the best of times, and it doesn't help that the camera control is awful. Part of this is because you use the d-pad to control the camera (inconvenient, since you're presumably already using your thumb to move your character), but that's not the only problem. The other problem with the camera is that the view is very limited. It's a third-person point of view, similar to that of Metal Gear Solid 3: Subsistence, but here Snake's body takes up nearly half the screen, making your point of view extremely limited. Again, not a good thing for a stealth game.
As with all Metal Gear Solid games, the first-person point of view is no better. It's only useful if you're stationary and trying to examine a single object up close. But try actually using it during combat and you'll find yourself taking damage quickly, unable to properly respond to your enemies. In combat, the first-person point of view is next to useless.
Finally, there is pretty much no in-game tutorial or explanation about how to use key elements in the game. You can create spy units to go spy on areas, technical units to make weapons and ammo, and medical units to make medicine. The problem is the game doesn't properly explain how to do any of this, which leaves you pretty much to figure it out on your own. There is a token help screen with a legend on how to do things, but it's missing key information, making it effectively useless. It's pretty much a situation of figuring out how to do these things by trial and error.
CONCLUSION
If you're a fan of the Metal Gear Solid series, then Portable Ops is worth checking out. If, however, you aren't a fan of Metal Gear, then Portable Ops certainly won't win you over, and will likely turn you off more than anything else. It's unfortunate because the story is actually quite good, and there are the makings of a great game here, maybe even a classic one. But there are simply too many problems for the game to be considered more than above average.