The first section trades Pepe for Jamacy, which quickly crawls along the ground when it doesn't have a ladder to climb. Pepe was a better partner for Nitron here as it was strong enough to provide a distraction, while this time both enemies die in one hit. However, the terrain is more deadly this time around, the Nitrons are more numerous and appear higher, and a couple of the Jamacys are placed where they could possibly knock the player into a pit, so it's a decent tradeoff.
Pole was kind of interesting thematically, but it doesn't have much to offer the gameplay and it's overused here. Potton is the only other enemy for the rest of the first half and he's not much of a threat by himself either.
After a pointless forced use of Rush, we find that Jamacys are crawling out of the broken walls. This one is alone, and beyond that is a new water section.
Now, the previous water section was hands down my favorite part of the game, and likely the most difficult. This is a joke in comparison. Instead of being attacked vertically and horizontally among complex terrain, we're treated to a wide open path between two enemies attacking vertically, meaning we can just sail right through without hassle. We don't even need to go after the refills, as it's short enough that it only takes 2/3 of Rush Marine's energy.
Rush Jet also works just fine in water, if you're so inclined. Yet more Pottons fill the room afterward, though these at least have a chance at hitting since the player might go for the ladder instead of walking under them first.
This section is pretty great though. There's a bunch of Jamacys falling from the ceiling, and they can climb down any ladders they run into. Having a horizontal section full of ladders was a brilliant move, as it provides a bunch of things for players to grab onto, breaks up the enemy movement, and there are plenty of possible routes to take, any of which are viable depending on the current position of the enemies. It's not that difficult, but it's one of the most interesting examples of stage design we've seen so far.
And then, an empty room. Okay.
This one does pretty well with half the stage, but also wastes too much space neutering the water section and spending a quarter of the stage on more Poles. Still, the new section was a great idea both mechanically and thematically.