Much, much better than many critics (Especially Gamespot) give it credit for, but not perfect. Read on to find out why..
First off, the campaigns. For an AvP fan like me, the plot was far better than the films and was surprisingly well done, with a couple surprising events to keep me entranced. Without giving alot away, it takes place after the events of Alien 3. When Karl Weyland discovers a Predator pyramid, the Predators leave their planet to get to Earth to eliminate the humans and remove all traces of the pyramid from Earth. But when the Aliens escape from their holding cells at Weiland Utani, it leads to a clash between the two races with the human caught in the middle. The plot was consistantly entertaining and I really appreciated the fan service through the audiologs, which reference events from the previous Alien/AvP films (make sure to find Weilands, his are the best). Lance Henriksen is as great as ever in his role as Weiland, and he makes for a creepy, powerful villan.
There are three different campaigns, and overall I would say they are all worth playing through, but the campaigns aren't exactly equal in the amount of fun you'll get from them. Each of the three campaigns takes place on the same levels, so you will revisit most of the same places, but I personally found that the game wasn't significantly hurt by this move since the campaigns aren't the longest I have played. I played each of them on Hard mode, and I finished the Marine campaign in 8 hours. This one is definately the strongest of the three, as it has deeper characters, a dark, creepy atmosphere that kept me on edge throughout, and probably the best realized story of the bunch.
The Predator campaign isn't too shabby either. I finished this one in only about 5 hours on Hard mode, but the Predator campaign is cooler in that it makes you really feel like a powerhouse over your enemies. The androids that give you a hard time in the Marine campaign cower before you in this one, making it a more fast paced action shooter, completely different from the survival horror in the Marine campaign.
Sadly, coming in at the bottom of the pack is the Alien campaign, which is below the other ones in every way imaginable. This one took me under 4 hours on Hard mode, and excluding the excellent first level is unmemorable and not much fun. It also has a pretty lame boss fight at the end, which I beat by repeatedly strong attacking until it died. In the end, each campaign is worth at least playing, but I'd only really consider replaying the first two.
Thankfully, the multiplayer is top notch and consistantly entertaining in every respect. Whether it's standard Deathmatch (FFA, Species and Mixed Species TDM) or one of it's other game modes, each game promises completely new possibilities with the 3 different races in check. Infestation is by far the best game mode of the bunch (think Halo Zombies) and one of the scariest, and Survivor Mode can be VERY entertaining when played with friends. Predator Hunt can also be great fun, but the only downer is that if you have a full 18 players, you might spend a long time waiting to get a chance to kill the Predator and play as it, so I had more fun when it was just one Predator and 3 other humans playing. Either way, there is more than enough here to satisfy FPS fans, and getting new unlockable skinds as you rank up isn't half bad either.
So at this point you may be wondering if there are actually any flaws in this package. And the answer to that is yes, AvP definately has it's fair share of issues to be worked around.
First off, the game only ships with 6 maps for multiplayer, nearly all of which are stolen from the campaign. They all work well and are fun to play on, but this really isn't enough considering how many maps shipped with Halo 3 and Modern Warfare 1 and 2, and unless you bought the $100 collectors edition of this game for 4 more maps, you'll have to wait until they finally get released to the general public.
It also had a couple bugs that can get on your nerves. Among other things, I wasn't allowed to walk through a door to get to the next room, I got trapped part way into the floor during a Predator mission, and WEIRDEST OF ALL, I got a 30 point achievement during the Marine campaign for getting 6000 EXP in Ranked Matches online. It boosted my Rank to a 25 and unlocked many skins, only to reset my rank the next day, still keeping my kills and death on the leaderboards as well as the achievementbut removing my unlocked skins. I don't expect this to happen to many people and some may like the free achievement points if it does, but it's an unusual bug that hopefully gets worked out at some point (dont believe me? Check my Gamertag, Dark Ninja 102). The dialogue is also flawed. Although well written, it is almost always delivered substandardly with the exception of Lance Henriksen's character, and some may be annoyed with some of the repeating lines by the Marines ("Don't let your guard down." "It's not over yet!" etc.). And although I personally thought the graphics were also better than critics thought them to be, some of the humans look too cartoony for my tastes and may turn off some people to the look of the game.
But overall, considering Gamespots score of 5.5, I expected there to be much more wrong here than there was, and I was pleasently surprised at just how good Rebellion's new entry in the series was. It has its flaws to be sure, but the gameplay is incredibly satisfying and brutal, the story is above average, and the multiplayer will keep you coming back for more and more, even if the campaigns may not. Variety is the spice of life, and Aliens versus Predator has it in spades.
P.S. The controls are fine. I have never had any issues with the controls offline or online. If the tranisition with RT for the Aliens isn't your thing, just look at the wall and jump. You don't slow down, you move much faster, and it's easier to do. If Gamespot really couldn't manage something as simple as that, maybe they need someone else to play the games.
The Good:
-Story bests the movies and is surprisingly well done.
-Lance Henriksen as Bishop!! Great performance, great villian.
-Brutal executions
-Marine and Predator campaigns
-MULTIPLAYER
-Variety, variety, variety!
-Great soundtrack that has a nice mix of movie themes and the familiar sounds you know and love
-Most of the boss battles
The Bad:
-Annoying glitches
-Non-Lance Henriksen actors
-Too few maps compared to most modern games
-Some graphical issues
-The Alien campaign
-Some (although not me) may be turned off by the graphic, stomach turning executions
The Ugly:
-The final boss battle of the Alien campaign. Seriously, lame. Just lame. You won't believe how easy and incredibly lame it really is.