I'll start by saying that I find it really interesting how similar the game storylines are. The first mission sees you escaping imprisonment and fleeing Dunwall, after being dishonored. The fourth mission has you infiltrating the home of the resident genius--both even feature removing Sokolov! Your allies turn on you (or reveal their true colors) near the final mission. I just find it fascinating.
And I'm going to say that I'm somewhat disappointed as well. Throughout the first game, I knew exactly where I was going and why. Every time. Each level was its own world, its own section of Dunwall, and it was obvious. II has got me confused about pretty much the whole plot. The Royal Conservatory felt like it was just there to pad gameplay time, and is disappointingly short to boot. The Addermire Institute is cool, yet bland at the same time. So far, the only places I've really been impressed by are the Clockwork Mansion (hello, stereotype) and the Grand Palace, mainly because I knew exactly why I was there and who I had to deal with.
Putting aside the crystal-clear plot, the Clockwork Mansion is impressive for obvious reasons. It's cool to look at, but people also had to actually script all that in. It's also just a really nice, objectively pleasing house, without all the moving parts. And I love that you don't even have to play Jindosh's game. You can shatter the ersatz skylight in the entrance hall and slip between the walls all the way to the lab's service elevator. And then you can just snipe his bitch-ass.
Speaking of Jindosh--he's such a satisfyingly infuriating character. John Gegenhuber does a really good job making him sound like an entitled, if brilliant, prick who doesn't think consequences apply to him. He's a creative, perfectly balanced upgrade to Sokolov.
The Grand Palace is impressive because it's one of the very few locations in II that has the exact same architectural magic as most of the buildings in I did. At just about any angle, it'll be beautiful, or at the very least interesting, to look at. The interior is fantastically done, and I love the twist of the Duke a) having a body double and b) him not being a dick.
Honorable mention: Edge of the World. Downtown and bayside Karnaca is really creatively designed, I love the central canal, and it's pretty easy to traverse. I don't really think it *needs* to be there--it's literally just a transition mission to The Good Doctor--but it's fun to play through.
I think that's about it for now.