I stopped watching for a while during the middle of Sinnoh. For me, the saga was too long, very boring, and highly repetitive. The only parts I actually remember enjoying were the Hunter J and Team Galactic episodes. Then I got back into the show during the beginning of Unova. It seemed like the show was going to get revamped and start anew to recover its former quality and learn from the mistakes from past seasons. Around the middle of the first season of the saga, I learned this was not going to be the case.
Ash acted as if he was in a alternate dimension where he went to Unova instead of Johto, because he was making careless mistakes and presented himself like a novice. I remember that part when he forgot how to catch Pokemon when he saw a Deerling. Then I saw Team Rocket actually being serious about their jobs. Too bad that was at the cost of getting their souls removed. And Team Rocket still failed in their jobs, as this time however they knew when to retreat before getting blasted off by the heroes. I also find the new companions a little irritating and uninteresting with their evaluations and little kid references. The first half of the saga had somewhat interesting plots, but its appeal did not last long While I was starting to lose interest in the series again, I saw previews for the Team Plasma vs Team Rocket episodes. They looked epic and seemed to be exactly what the saga needed. I was exited to see the show take a more mature route in these episodes. But then WHAPAAAA! An earthquake struck and cancelled the episodes. After that, I decided to stop watching it as the series did not appear to be releasing any interesting episodes for a while.
I haven't completely abandoned the series. I look at some episodes from time to time to stay up to date. But other that that, I don't frequently watch the show anymore. I really do wish for the series to evolve into something similar to what the B2W2 trailers showed. That type of maturity and complexity is what the storyline needs to truly improve, in my opinion.
I still play the games and am looking forward to the X and Y games.