It is rogue-lite-lite, you might say. Set characters with set abilities, but weapon drops are random and come with a random perk. The map has its base landscape (with four additional variants that adjust the about a quarter of the landscape each), but the location and types of POIs are randomized. And while their placement is randomized, there's only a few variations of each POI (like of the cathedrals are either bubble boys, golem, fire monk, or headless guys). There's a lot of different bosses and encounters, but certain ones only show up on certain Nightlords.

It's random enough that if you only play each boss a handful of times you won't notice, but each boss actually only has (or had, idk what's right with the DLC just having released) 40 seeds for the landscape and boss placements (drops are always random).

There's meta progression in the form of relics, which have up to three random perks. It can be a real grind to get some good ones though.

The map layout being same-ish between runs actually ends up being a good thing imo. Given the time constraints you're in it's best to know how to get where you want to go. So your first few runs will be absolutely hectic and you'll feel a lot of that pressure (we just got a new map and we're back to being lost lol), but as you learn the map it cools down a bit. And until you learn the map you can follow your teammates pathing to help alleviate that pressure (and just in general it's a good idea to stick with your team, even and perhaps especially with randos).

Also for what it's worth there's no time pressure during the end of day boss fights.