As a big Thief fan who played the first three games, the trailers and info I've seen so far have left me with mixed feelings. There are copious nods to the original trilogy, like the character of Basso and his pet bird Jenevere. But there's also a lot changed. From what I've seen of the gameplay, it looks like there's plenty of stealing and sneaking to be had. I'm definitely not too enthalled about Stephen Russell being dropped as the voice of Garrett, though; that man basically owned the role in the trilogy.
I do wonder a bit about Garrett's new characterization. As folks have said, he's always been the snarky cynic, doing what he does best to make his way in the world, less out of some kind of existential desire to "be free" but more because a man's gotta eat and keep a roof over his head, and nicking it out of someone else's pocket is his forte. You got glimpses of his underlying heart and care for others from the games as he would ultimately do the right thing, but not until he'd fully expressed how exasperating it was it came to this. He took pride in his work and loved a challenge, but he wasn't being all poetic about it constantly. His new character design, I admit is slightly off-putting. I don't have a problem with the face mask (it fits well enough) but the eyeliner-ish look to his face is a little too goth-like. The new voice actor isn't bad, but I'm not sure he really brings the right attitude to the character yet.
Well, I'm still willing to give the game a go, no matter how many apparently parallels to Dishonored it has. That game itself wasn't all that bad either, so who knows, maybe the new Thief will improve on its weaknesses and be a worthy successor to the original Thief games.