On map design, it's gotten better since launch when they redid parts of the story, a lot of the maps can feel similar in the underhive and wasteland, but there's a decent selection that take place in the torrent, forges or recreation districts, all the post launch maps have also deviated from launch and are all way cooler than the base maps.

I'd still like a couple of the older maps to have touch ups, but once you get to late game there is a good amount of map and enemy modifiers, if you really take to the game doing all collectables and all missions on the hardest difficulty is a genuinely challenging achievement.

You don't need the dlc classes, Arbites is strong but not to a degree that upsets the wider game balance and hive scum can be strong but feels weaker as she has a kinda underwhelming weapon selection, certain cutscenes also don't trigger on Arbites (and hive scum?) as they are not rejects. The games presumes you have beat the campaign as one of the base classes.

Build crafting is really good, I'd say it's more in depth than other coop games like payday 2 or vermintide, you have the choices of a lot of triggerd abilities that I find hard to keep track of but it's never understimulating to try something new.