The gameplay itself is very important. A game with good graphics and music, but without proper gameplay is no fun.
Yes, I know some gameplay elements need other gameplay elements for eachother to work better.
Gameplay and content.
What's content? Well, not story, but characters, world, concept, etc.
Something like Mario Galaxy or Wario Land 4 has interesting content. Something like New Super Mario Bros 2 doesn't.
Good gameplay and a boring or offputting concept gives you a tech demo or gimmick game. Good content and mediocre gameplay often gives you a cult classic. Both gives you a game people will remember for more than a few month or so (like say, Ocarina of Time).