I finished the game on Saturday and my overall impression matches you initial one. When looked at from a technical and game mechanics standpoint, there's hardly any reason to complain. It's optimized well (runs smoothly on my PC with settings maxed out), it really is a stealth game where action is truly a last resort that only works when facing up to two, maybe three enemies at once. There's a lot of stuff to do in the game with numerous optional missions and places to rob. The atmosphere resembles the previous games, etc. There are also some pretty cool options that most other games don't offer, from additional difficulty modifiers to UI options.
The negative stuff for me are:
- a mediocre and predictable story (even some locations have already been seen in previous games
*cough*abandoned, haunted asylum*cough*
) and this increasingly popular vulgar style of writing. Correct me if I'm wrong, but I don't remember the previous Thief games had much swearing in them. (I'm not against vulgarities, mind you, I just don't think they fit well everywhere)
- music that doesn't really fit the setting. To me at least, the music sounded way too modern in a lot of cases.
- an unnecessary reboot. There really was no need to do a reboot of Thief. The story, as mediocre as it was, would have worked perfectly as a sequel too. In fact, since this game was originally announced as Thi4f (with the old logo styling and all), I'm pretty sure it was written as a sequel and then slightly altered to work as a reboot.
Most importantly (and this last point is the most difficult to define), the game just doesn't have that something that keeps your attention. For me, when I play a game for the first time, if it's any good, I'm usually thinking "just a bit more, just this one more section and then I'm done", basically it draws me to see what happens next in the story and to play more. With this game I was usually thinking "I'm finishing this damn level and that's it for tonight" and then I put that thought into action. And this wasn't due to the game being difficult, it was actually relatively easy, but it quickly became cumbersome for a reason I can't really define.