There are barely any enemies in any of them that I've seen. It's much more a series of small puzzles you can tackle in any order. Again, just like the Divine Beasts were.
One dungeon is mostly based around using trampolines to fly around and icicles to attach to things as levers. Another is based on using mine carts to go up/down levels while you shoot switches to change the tracks. Another is just a big open area in the sky with some water pools in it.
There's like... a black bokoblin or two in there? Some blue chuchus, if I recall?
Worst part is that because they don't know which dungeon you'll do when, they replay the same cutscene at you every time you beat one - and it's a long one. Yes, the companion changes, but it's almost word-for-word the same.
But on the other hand, they DO fit in with the world around them, they ARE elemental themed, and there are classic Zelda bosses that DO reward you with heart containers. For a lot of people that might be enough. It's not like the Divine Beasts where they even looked like the basic shrines. But if you're someone who can analyze game design, you'll easily see that they're just the Divine Beast-style dungeons in fancier clothes.
EDIT: I will say this, the *approaches* to each dungeon are pretty fucking cool, and if you consider them part of the overall experience then that elevates things a lot. It's just linear platforming and puzzle solving on a treacherous route to the dungeon itself, whether in the sky or underground, but it's fun as hell.