The guy was carrying his scratched headband for like 3-4 years. Not to mention he based all his training on saving Sasuke, and let himself get consumed by the 9 tails for Sasuke. And people like Gaara, Itachi, Sai and even Sasuke himself have asked Naruto why he would go so far to save someone like him. Honestly, Kishimoto should've renamed the Manga to Sasuke and company. I would understand completely if they were "actual" siblings or at least knew each other for years, growing up close.
I've seen a LOT of anime, manga, movies, series etc, but yes Naruto has the worst ending out of all of em. No it's not just the pairings. Pro-fans need to stop using that excuse. The story began to die way earlier it just reached it's total crapcakeness around 2010.
Man, Curse, you nailed some great points here.
As for endings I've seen, Naruto really did have one of the worst endings I've seen from a manga. And I knew and felt the ending for Negima! as rushed as it was wa spretty crappy too if it couldn't even show and tell us s tuff until UQ Holder.