Long, grindy, and generally low-threat slaughter. Combat choreography is largely absent and the majority of the map is occupied by clusters of the same monster blocking your path. Speaking of blocking, monster block lines are often employed in strange ways, allowing the player to door and hallway camp the enemy hordes. Potentially deadly traps are neutered by frequent invul spheres which enable trivial BFG facerolling. Detailing ain't too hot either, with the majority consisting of monotextured square rooms and hallways. Some cool sector work is present among the minimalism and the scale of the final area is certainly impressive (the 300+ Cacos which take years to float into firing range, less so). If you want to spend over an hour spamming BFG and rockets, I suggest you play (or replay) Cybersky instead by the same author - it looks and plays better.
Frankly, if you're looking for more Plutonia, this isn't the deal. It's very different, but it's still very good in every aspect. I'd recommend it not for having the Plutonia name in its title, but for being such a good wad in itself.
Being that this was made by a lot of people™, it'd be impossible to talk about how each map performed, but they all pretty much draw resemblance to each other, while also possessing some of the designers' unique quirks visibly into them. Nothing's perfect, so there's a handful of levels that either aren't made for most people or straight up suck (like MAP15, and, arguably, 25).
Every level is challenging, even more so than the original Plutonia ones, though it still possesses Plutonia's design of combat of placing the player between a rock and a hard place in nearly every area, sometimes executed poorly, like trial and error, which can feel unfair.
Visibly beautiful and playfully slaughterful, fitting with its great soundtrack.