For a long time on /a/ I have seen vociferous complaints about the filler episodes which make up the last third or so of the first Naruto series. Aside from the fact that they are not adaptations of the original manga, why do fans hate them so much?
I am watching the series via Cartoon Network's broadcast, which just finished the mini-arc about the Bikochu beetle, and have not noticed a significant drop-off in artistry, production values, or storytelling quality in these filler eps compared to the last 3-4 dozen pre-filler eps. Granted, these are side stories only vaguely connected to the overall storyline, but the so-called "overall storyline" was so paper-thin to begin with that I don't see that it matters. The style, humor, action, drama, and character development components all remain pretty much the same, and it's nice to see some characters in action that have been prominently featured in openers but given little or no attention in episode content over the past few dozen episodes. (Especially Hinata in these most recent episodes - quite impressive, actually.) It's also been quite satisfying to see Sakura finally discovering a role for herself where she can excel.
Now granted, except for the odd episode here and there I haven't had a high opinion of the series since the end of the attack on the Leaf Village arc, so maybe that's why I haven't noticed the quality drop-off, but so far I just don't see what people have been complaining about.