Pros:
+ Best game in the trilogy
+ Combines everything that worked in 1 and 3 to make the near-perfect Metroid Prime experience
+ Very interesting lore
+ Arguably most difficult game in the trilogy which is appreciated
+ World is designed to be the easiest and most convenient to backtrack out of any game in the trilogy
+ Closest to a horror game the franchise has been alongside Fusion and Dread
+ Character designs are the absolute best in the trilogy, with Samus' suits being a major highlight
+ One of the best item progressions out of any metroidvania
+ Main mechanic of switching between Aether and Dark Aether creates very satisfying puzzle elements

Cons:
- Aside from a few key locations, the entire world is very drab and samey-looking (while this does add to the world's realism, it detracts from the stunning vistas that 1 and especially 3 are able to offer)
- Music mostly isn't as memorable as in 1, but still a bit better than most in 3
- Boss designs oftentimes look almost identical aside from a few great exceptions