Got the game myself today and played 4 hours. I am really enjoying it (and yes, I played the original back in 1998).
I like that you can choose how you want to solve a situation. Sidequests are also nice, I feel there's a lot of content here. I also like the small riddles that come every now and then. Keeps the game from getting boring. Can't say much about the story, there really didn't happen too much until now. But I don't really care about the story tbh.
As for the negatives, the graphics are somewaht mediocre (playing on PS4), it's really not what you would expect from Next-Gen. Don't get me wrong, the game looks nice and all, but just not jaw dropping. Also kinda disappointed that it isn't 60 fps, it would have been possible definitely. If you don't have a next gen system yet, you can get the game for PS3 or 360 without problems. For those systems, the graphics are actually pretty good.
The long loading times are also nothing to be proud of. But hey, from a technical standpoint, the original Thief did also disappoint in 1998. So I guess it's true to its predecessor? Yeah, not really. It's true that not everything is the same as back then. But then again, why should it be? What's most important is that you have fun playing the game. And I would say that's definitely the case here. Fighting won't get you anywhere, even on normal difficulty you have to sneak. In fact, I had a harder time fighting than I did back in the days with the original! You don't even have a sword now! It's what I expect from a Thief game in 2014. The gameplay is different compared to the original, but it isn't bad at all. It's something you won't find anywhere else, it's still unique to this very day. There's really nothign you could compare it to. And that's why it feels fresh to play the game. At least for me that is.
So far I think this is easily an 80+ game. I don't get why it's getting so much hate.