Batman: Arkham Asylum

  Pros

• Combat mechanics are simple, but fun and flows well. It's entertaining to watch.
• Great in terms of both visuals and sound, it makes for a great atmosphere. Includes voice acting. Pretty good all round.
  
• Not too much combat. Beating stuff up is fun but Batman is meant to be an awesome detective as well and it lets you be one in this game - mainly by solving Riddler's Riddles.
• Story is good and well told.
• Appearances are made by many a classic and some not-so-classic Batman villain, if they're not seen in person you'll usually find some hint of them somewhere in the asylum, which is pretty neat.
  

Cons

• You'll probably use detective mode A LOT and the blue filter that comes with said vision mode kind of spoils the visuals somewhat.
  
• Kind of crummy end boss.

 
In Batman: Arkham Asylum you'll pretty much split your time between three things - straight up combat, stealth game play and detective work.

Combat is a pretty simple affair.
X hits stuff. Y counterattacks when you're about to get struck and B is a stun move that you'll occasionally need to throw in when you come across certain enemies.
While simple, combat flows awesomely and is fun to watch.
It's extremely satisfying to take out a whole group of thugs.
You can use your Batarang in combat, but except against certain larger - charging enemies it's a fairly useless combat implement.

Stealth sections will usually see you on higher ground, typically on conveniently placed gargoyle heads - whilst you stalk the various thugs in the area. Stealth sections are pretty fun as theres a decent variety of ways to take people out.

You can set up plastic explosives and detonate them when a foe walks by - or if you have the upgrade they'll detonate themselves via proximity.
You can wait for a dude to walk beneath your gargoyle and then you can string em up from it.
You can hurl your Batarang at a dude and while he's dazed on the ground, leap down and finish him before swooping backup to your gargoyle.
You get the picture.

One of the things that make the stealth sections so awesome is that as the enemy numbers grow slimmer they'll start to panic more and more - practically begging Batman to show himself and end the suspense, shooting around corners randomly, sobbing. It makes slowly whittling down the enemy numbers extremely satisfying.

The detective stuff is also quite satisfying and The Riddler factors into this in a big way.
I guess it's essentially a glorified collection mini-game, not too different from what other games do and I generally hate collecting stuff - but it fits The Riddler's shtick reasonably well and it rewards you by unlocking challenges for use in the games challenge mode, trophy's - which are basically the games models for you to look at and character bios and interview tapes which are pretty interesting either fleshing out the characters some or just because they're amusing.

None of the actual riddles are too difficult, though finding them can be a bit of a pain at times.
Fortunately The Riddler isn't the genius he thinks he is and he has left maps detailing the locations of his riddles and trophies and other assorted goods which makes things a bunch simpler and pretty much overrides the problem I have with collection in games.

I forgot to mention detective vision.

It puts a blue filter over the screen, highlights objects of interest - The Riddler's stuff included - and allows you to see enemies through walls which is pretty rad and makes the stealth sections simpler. Helps you track them easier. Unlike most stealth games you're not hiding to avoid the bad guys, you're hiding because you're lying in wait. You're Batman! You're a Badass. You wait and you strike.

In some sections you'll use detective vision to look for clues. They're simple enough to find, the game highlights the area it's in you just have to look for it. Once you've found your clue you'll collect a sample of whatever it was you found, say a hand print for example and then you can use detective vision to look around and follow the hand prints someone left to track them down.

The main problem I have with detective vision is probably my main problem with the game as a whole, you come to rely on it too much. It'll help you spot foes, it'll help you solve The Riddler's riddles, it'll help you find alternate routes and so you'll probably keep it on all the time. At least I do, I turn it off while in combat so I can admire the games fantastic visuals some but as soon as the last punch is thrown I'll switch it back on and there'll be that ugly blue filter over everything.
I think detective vision could be just as an effect a tool without the filter.
It could still highlight objects of interest and dudes through walls without it.

As you progress throughout the game you'll gain XP which you can use to upgrade your skills.
Through multiple Batarangs instead of one, throw guys in combat or the proximity explosives for instance. And as you progress throughout the game you'll also get more gadgets. Like said explosives for instance, or the Batclaw which will help you pull down walls and vents in hard to reach places.

It's been said that the game has a ' metroidvania' feel in that regard, some places are inaccessible until you've collected a certain upgrade or gadget and that's especially true for when it comes to The Riddler's riddles etc, which are often out of reach until later. The game certainly rewards exploration.

I don't know what else I can say. The game's pretty awesome and I'd say this was one of the few cases where the prerelease hype was, in the end, warranted.
It's a great game, THE best Batman game yet and probably the best Superhero game in general for that matter. I'm hopeful other developers of other Superhero games look at what was accomplished with Arkham Asylum and see that Superhero games don't have to be some shitty movie-tie in thing pumped out for a quick buck.