As long as the core gameplay's good enough, it doesn't matter how repetitive the experience is. The best example for me is the sports sim genre. A faithful recreation of a sport, that accurately reflects the dynamics of the game while controlling well and providing a decent challenge, can eat up more of my time than any RPG or adventure title, even though it's essentially the same experience over and over again. The same goes for fighting games. A tightly designed beat 'em up of sufficient balance and complexity can attract a dedicated fanbase and tournament scene, even though the core gameplay doesn't vary much from bout to bout. Maybe that's not the sort of repetition you mean, though.