A maligned series that contains some of the best games ever made.
Super Metroid and Metroid Prime are two of my favorite games, and arguably the greatest games on their respective platforms.
The rest of the series ranges from pretty good to absolutely terrible. Metroid works best once a generation. Give it to the best developer available and let them create a masterpiece, then the IP goes back on the shelf.
And for Christ's sake, no dialog, no speaking characters, no Samus out of her suit (until the credits roll,) no cutscenes. The scanning in Metroid Prime is as much text as the Metroid experience can support.
A solitary, silent journey through a beautiful and hostile alien world is Metroid. This focus is what makes Metroid memorable. Cramming a bunch of extra shit in ruins the experience.