Don't buy it expecting to be able to play Crysis at its highest settings. Heck, don't buy any 5.5 lb laptop and expect it to be able to play Crysis at its highest settings. If you want to "hardcore game" on a laptop, you need to buy a brick (9-10+ lb machine with 45 min battery life). At that point it stops becoming a laptop and starts becoming a mobile desktop (which is personally not what I'm looking for).
The MBPs are good if you want a relatively light machine, all-around power and decent battery life. The high end 15" should get around 5-6k on 3DMark06, which is more than enough for most games. Go out to Bootcamp and you should have decent FPS in just about everything. (The fact that its screen is only 1440x900 also helps -- less pixels to push around).
The only reason I can see not wanting to get these is if you need certain things: Expresscard, Blu-Ray, eSATA, etc. I personally use none of these, so I'm cool with the machine as is.