I don't like the idea of cutting down species - frankly, I can't think of two I'd play in the same way. I mean, take Centaurs and high elf hunters, for instance. In the first case, I usually go for AC and don't worry about magic. In the second case, I usually try and get some translocation spells going.
I for one love the new vaults designs.
I do agree with the thing about the labyrinths, I think they're really great thematically, but in terms of gameplay, pretty dull. It would be nice to work out a way of intensifying the puzzle-solving aspect of the labyrinth so it wasn't just a simple matter of persistence. Just off the top of my head, wouldn't it be possible to have the correct route form a mathematical sequence, so the only way one could get through would be to recognize the pattern?
I mean, for instance, from Conway's game of life:
there are loads of pretty simple but interesting series, that could be materially represented in the structure of the labyrinth.
The other weak part of the game I think is the hell branches before they end. Thematically, they''re nice, but in terms of play, one tends to just run through them. Some incentive to actually explore would really help them. (Also, I can imagine all sorts of fascinating vaults and features that could work to really flesh out the idea of hell on DCSS. There's a great lovecraftian vibe in some of the monster descriptions - I think some demonic courts, circles of babbling cultists, lost madmen etc would really spice up the hell levels).
All that said, DCSS is honestly the best game I've ever played - I've played it for about four years(?) now, never won once*, and enjoyed every minute of it. Good games are good stories - that's the reason why people still play the old X-com, or alpha centauri. It's not because they have slick mechanics or some feature that no other game has. It's because they make you believe in an engaging situation, in a comprehensive way. A lot of re-launches of old games make the mistake of doing away things that helped the story to make the game more streamlined, but it's always a mistake. The new X-com, for instance, got rid of base attacks, because frankly they were a pain in the ass and a hassle all round. But, losing that, they deprived the game of that thrill of fear you used to get when you saw a battleship looking for your base on the radar. DCSS is better than a lot of other dungeon crawlers not because it has a better feature set, but because the writing, and the story, is so much more engaging.
*Don't ask.