One thing I don't get is, even though they're only showing "filler episodes", why leave out some main characters from these side stories? It wouldn't be hard to add them and still not conflict with the manga. Like where are Kakashi, Sakura, any of the jounins, Jiraiya, etc? I can understand them not wanting to mess with the Sasuke or Orochimaru characters, but these others would be fair game for developing histories and back stories without straying from the manga.
It also seems the same few genins are being used, like Hinata, Lee, Neji, Kiba, etc. I'd rather see more of Shikamaru, Ino, Shino, etc in longer story arcs. I think Ino will be in episode 192, but it's a one episode arc.