It's my favorite Zelda. It's dark, weird, and completely different than any other Zelda game. You have 3 in-game days before the world is destroyed and you have to play the song of time to revert back to Day 1. Certain items are lost and actions are undone if you go back in time so there is some pressure to accomplish something meaningful in that 3 day span. Also masks play an important role in the game. Certain masks transform you into other creatures with new abilities like a zora, goron, or deku scrub. All in all it is a great game with really unique features that haven't been seen in other Zelda games. In my opinion I felt like OOT was really bland, I always thought MM was the magnum opus.
I would say pick up MM and Zelda Link Between Worlds which is another solid title, and MH4 if you really want to become a no-lifer 
