I guess I should mention, Other M's like the only Metroid game that has a postgame. After the credits you can go back into the game and you get a bit more story and an extra objective. It's mostly just for being able to freely explore (finally) and try to collect everything, but you can miss out on a pretty fun (IM0) bonus boss. 100% isn't required to reach that extra objective and boss, btw.
Game collection: http://www.backloggery.com/bakonbitz
Gaming channel: https://www.youtube.com/channel/UCwVQm69J7bGScbv3_50C0dA