LogFAQs > #906032123

D (at least with fewer >s).

I love Echoes and think it improves on 1 in some respects (e.g. bosses), but still consider 1 the best Prime game.

The main reason is the structure, which you mentioned. 1 has fewer "hard" locks (i.e. where the story rather than your / the character's skills impede progress). Also, 1 lets you find the keys at any point (provided you can get to them), whereas 2 only lets you get them after a certain point in the story.

As for the planets they take place on, Aether feels more alien to me, but I find Tallon IV more interesting for some reason. Maybe I just like the familiarity of having a "green" area, a snowy area, a hot area, etc. It's not really a coincidence that the Phazon Mines are my least favorite area in 1. Aside from the wonky difficulty (particularly the first save point being too far away), I'm not a fan of the aesthetic.

In terms of the puzzles and power-ups, 2 probably is a bit more creative if I'm being honest. The enemies too (including the bosses as I mentioned).