DL'd the demo this weekend and it looks awesome. A cross between Splinter Cell and Assassin's Creed, with some very smooth gameplay and fantastic graphics. Batman: Arkham Asylum
The "corner takedowns" are particularly impressive.
Bought it this morning, absolutely amazing. Can't recommend it enough. Like you said, Splinter Cell/Assassin's Creed with the detective bits of Condemned. It reminds me of Chronicles of Riddick: Escape from Butcher Bay in places as well.
Well, for your son (of course) it would be a great game to show off the capabilities of the PS3. And if your son happens to get sick of it, and you happen to play (just to keep the PS3 ticking over, of course), then you'll find one hell of a lot of things to do (challenges etc).
Bought the game this weekend, and gave it a good couple of hours last night. Truly awesome game, one of the sexiest PC titles I've ever played (especially when Harley Quinn bends over and you can see her chuff... but I digress, and will provide screenshots when I get home). I'm running it on a Core 2 Duo with an nVidia 8800GT, which isn't exactly top-end anymore, but I've yet to have any graphical issues despite the setting being turned up to the max.
Well worth paying for, especially since their nod to anti-piracy code means that dody versions have core functionality chopped out - you can't glide with your cape on a pirate copy, and just fall like a 'tard.