I played a little bit of it. It's a mediocre RPG that tries to build on what Mass Effect did. The actual gameplay itself is rubbish. The only redeeming qualities are the conversations, but truthfully even those aren't that interesting.
Check out some of the reviews for the game. They're all over the place. Half of the reviews slam the game, and the other half generally praise it. It's one of those games that's hard to recommend because you'll either like or hate.
I ended up getting my stealth fix by playing the splinter cell series instead (no rpg elements, but the gameplay is ALOT better than Alpha protocol).