I agree that they should not rush the content just for the sake of giving the players (aka beta testers) some content but I was not really disappointed with the screenshots. Of course the mobs that you will encounter in them will be the same type of mobs that you find in the area the dungeons are, it's only logical. They could reskin them slightly of course. The bosses on the other end is what matters, they need to be unique not just an oversized toad. With just 1 screen for each dungeon, it's hard to say that it looks copy/pasted. Even if it uses the same texture/coloring, it can be different as a whole and doesn't feel copy/pasted, but we won't know until we try them. And it's also normal that the dungeons theme are similar to the area they are in, else you'd be complaining about the transition being off.

but for the sake of the OP, I agree that no content should be rushed.