The goblins are incredible. I mean, phenomenal, great work. They really stand out as a group and a culture. You can feel what the goblins are. See and hear what they're like. You definitely know a goblin from another racial type.
The duergar are great. Very well done. I feel like they're a clan, and I get a sense of who and what the duergar are. Nobody drughs with clan Flameshade.
But then...
All of sudden the races just sort of merge together. They become costumes. An elf, a human, a whatever, doesn't matter.
Consider the drow in Moonrise. Do they feel like drow? Can you point out which ones are drow and which one is a wood elf and which ones aren't, without examining them?
Once you're in the city, it's suddenly like the NPC races are determined by random dice rolls. Could be an elf, a dwarf, a gnome, a human, a half-orc, whatever, doesn't matter.
I think this is very bad for the story and worldbuilding. I suspect it contributes (not the only reason) to why Act III doesn't feel as strong and compelling as the other acts. (Act II is carried largely by the cursed Thorms and the dark mood.)
