Well Yahtzee has only come up with a few reviews I remember being positive. Of them he recanted one (Grand Theft Auto IV) later on, in light of the much superior Saint's Row 2.
That said, Mass Effect 2 isn't a pure shooter, and what shooter elements it has rely heavily on the whole "Chest high walls" thing. It's also dialogue heavy and that is something that has gotten him to pan games before, since he REALLY hates lengthy bits of character development and storytelling.
In short, I'll be surprised if it he likes it, because it doesn't seem like his kind of game on paper... we could be surprised though.
I expect him to go into his normal rants, and then make contridictory claims about a story that doesn't make any sense, and too much dialogue and exposition which he shut off/ignored/made sandwiches during, perhaps explaining the first point. I anticipate he'll pan the tiny number of remaining RPG elements, call the shooting aspects derivitive chest high wall fests (as mentioned), and then slam the minigame.
He might throw us a curveball, but I'm not holding my breath here. Especially seeing as I think this game deserves a lot more criticism than it has gotten (though in an opposite direction in my case, since I think it needed a lot more stats, gear, customization, and RPG aspects).
Oh yes.. and to end this ramble...
I would expect Yahtzee to also complain about his fish in the captain's cabin dying, because he didn't get far enough for his hawt secretary/ensign to feed them for him. But then again buying virtual fish, never mind checking on them enough to notice they died, would imply he has a soul... and this is Yahtzee we're talking about.
I doubt he even bothered to recruit Boo as his cabin boy.