I've owned all of the major games since Gen 1, and, well, honestly, I've grown bored of it. Pokemon will forever be a part of my life that I love, but it no longer holds my interest because the series really hasn't changed much. Sure, it's grown as new things keep getting added, but the main goal of the game is the same - collect all 8 (or 16 badges for Kanto/Johto) and all the Pokemon. I can pop in Diamond version into my DS, and Black 2 into my DS, and feel like I'm playing the same game with different scenery.
It really just is getting to the point where it's tooth and nail. I agree with the last 2 posters (at the time of my writing) in this thread.
While I may not ever beat Black or White 2, (which I've had since launch, got both the Japanese on launch day at the Tokyo pokemon center and the English on launch day at my local Target store), I'll still love the series that pokemon is, but I think I've outgrown it.
I'll still flaunt my Espeon tattoo, though - I may be tired of the series but I still have mad respect for it.