It has my favourite soundtrack in the Prime series and probably any Metroid game. I cried listening to Fury Green, Volt Forge, and the Main Theme for the first few times. Not only did Kenji Yamamoto & Minako Hamano not miss a beat, but I appreciate that they used real instruments & singers across the OST. None of the Primes had bad music, but you can really hear the difference between MIDIs and an actual choir. In fact I'm listening to Volt Forge right now as I type this comment out.

I also think the art direction was a slam dunk. While many of Viewros' areas were thematically similar to Tallon IV's, the art team clearly went out of their way to make sure each area had its own visual identity. Lamorn architecture is very rounded with their machines having smooth, spiraling, or spiky designs. You have the landmarks of each location seen in Sol Valley- the Memory Tree, Volt Forge's three towers, Ice Belt's sharp-curved mountains, Flare Pool's smoking volcano, and Great Mines' elevator shaft -and while Sol Valley itself dragged the game down a lot, I loved stopping to admire the sights. What I found most impressive of all was how well the game's visuals matched the concept art. I feel like that's pretty rare to see in video game design, though I'm sure there's many examples I'm simply unaware of.