I got stuck with Thief Gold, so recently I have started playing Thief 2, which I didn't know much about, except, that many people easily say it's better than the original game... (spoilers ahead)
Here is my thoughts after playing the first missions of Thief 2: The Metal Age.
Most people didn't like in the first game, the supernatural elements. I largely could tolerate it, but never liked it. Probably that's why I loved so much the Lord Bafford mission. Classic get in, look around for loots, steal the big prize, get out.
After Thief, the City has changed. I like the lore very much, and there are some big changes. We are really steampunk now. We have lights more than torches, and of course lot of mechanical things, metal which makes sneaking harder, but more fun too. And a more modern settings, like security cameras and robots
The Mechanists are a new faction, grew out from the Hammerites. They are a major force.
So far the missions are more coherent and I like them more too. One of my favorite is, when we got captured, but we managed to escape and we have to sneak through parts of the City to Garrett's house to get some stuff...it's not easy, and when we get to our house, there is a nice surprise!
It feels more Thief-y, like we are really a master-thief who really treats this as a profession. And of course keep out of sight of these different factions. Especially after the first game, we don't really want to get into their mess.
What I like that we got some new items, like potions, and some gadgets, but it feels organic, because a lot of things have changed. For example there is a spy ball that we can just drop and look around with, without exposing ourselves (and later we can pick it up!). It totally fits, since so many things are modernized.
Stephen Russell is awesome as Garrett, and the sound design is still amazing. The level design become more realistic, as the game and story moved away from the supernatural.
I also feel that maybe the A.I. become better compare to the first game.
Some thoughts about missions so far (SPOILERS)
First mission is basically a tutorial. Basso is getting married, but his partner is locked in a giant mansion. The mission is straightforward, but you can go anywhere of course. I like these kind of tutorials more, as it fits more into story. Still no handholding, you can do whatever you want...
Second mission we are at a shipyard where basically can rob the whole place. Pretty fun stuff.
Third mission we have to frame some official. Can be some backtracking, if you are not discovering the hidden pathways. Also turn off the alarm switches help, hehe.
Fourth mission this is the mission I have mentioned above. We got sold out and we got captured, but not for long.
Fifth mission finished it yesterday evening, we sneak into the Mechanists chappel to eavesdropp. There is a pretty big spoiler in cutscenes, so I don't spoil it. Let's just say that Thief 2 really turned into an intriguing story, and I can not wait what happens next.
Sixth missions of course I can't count. I am ON the 6th mission, not after it.
You can buy Thief 2 on GOG, it's now on sale part of the winter sale. It doesn't have a huge system requirement, playable on a laptop, and doesn't bring your system down.
If you are stuck, I can recommend The Keeper's Chapel guide. I myself use guide less and less this time, and I enjoy the surroundings and challenges much more than in the first Thief game.