It's mediocre.
Stealth mechanics are lacking, which is weird since the game relies on sneaking around so much.
Also, time spent in the markets always felt lonely - as they're is so little to interact. However, that said, listening into conversations to find missions is pretty cool.
Though, with so many bugs and crappy AI enemies, the game is a bit of a joke.
Actually, while writing this I realise that the game is actually crap. Don't bother - play MGS or AC if you want good stealth.