I have to agree. I realize that the target audience is younger kids 8-12 years old, but did Nintendo really think that us veteran players wouldn't see the pattern with Ash, Pikachu, or Anybody for that matter, and ask ourselves: "Why don't they ever age??"
Ash went from being asked to be a frontier brain, to nearly winning the Sinnoh league, to being a clueless 10 year old once again in a new region.
Like Galdr said, Pikachu
should be like level infinity by now, but he seems to drop back down to level 1 with each new region.
Another thing I don't particularly like about Ash is that he gets so emotional. I can understand being emotional to an extent, but with him it's over the top. A good example is the Lucario and the Mystery of Mew movie.
I'm putting the example in a spoiler in case you haven't seen it and don't want it spoiled for you before you watch it.
I also think Team Rocket should appear a little less often. Maybe every few episodes or so. Not every episode. I'm pretty sure people have noticed that in the vast majority of new episodes, Team Rocket or another team (Galatic, Plasma, etc.) ALWAYS appears.
Despite all that, I'm not all that annoyed by Ash. Mainly just when he gets over emotional over things. Maybe it's because he has a Pikachu ^^ xD