I stopped watching the anime after the Johto Journeys season, but that was mainly because they didn't air it outside of digital television in this country, which at that point in time I didn't have, and this was before the days of Youtube and the various websites that upload anime, so I didn't have a source...much to my chagrin.
I started watching the anime again in earnest when Diamond and Pearl started airing, and I managed to catch up with what I'd missed (although I really wish I hadn't; the rest of Johto was good, but I didn't much care for the Hoenn or Battle Frontier seasons) thanks to online videos and DVDs. I've stopped again now that the Sinnoh seasons are over though, because I don't like Best Wishes. I don't like the art style, the fact that everything has been reset again, and I don't like Cilan or Iris either; Dawn was one of my favourite things about Sinnoh, and I don't like how she's just been discarded, and Cilan...well, I suppose I don't dislike him, but I don't like him either. He's just there.
I've kept half an eye on it because of the cameos, and depending on how it turns out I may watch it when it's all over, but for the moment I'm not really all that interested.