I started Halo 3 in 2008 (Online Multiplayer/xbl).. So... Yeah...
But no I didn't get tired of Halo 3; played it until reach came out. Will never get tired of Halo 3.
Reach is still fun but I play other games so that is prob why it is still fun. For me Halo 3 is now unplayable because
1: The connection
2: Halo 3 takes more skill and I've lost it.
3: I play other games.