About Naruto ending, the reason that the fanbase is splitted in two was technicaly and obliviously shipping.
None of the shippingers, specialy NS fans didn't care about characters like Taka, Yamato or Orochimaru and never cared about any logic errors of the manga till chapter 699, but after that suddenly the critic borned in them.
The ending was typical long running shonen fight ending like Kinnikuman, Dragon Ball Z, Hokuto No Ken and Kenichi - tons of things left unanswered or forgotten and some not important characters are left out. That's the problem with all of of these long running serieses, the longer they are running the lowest chance that it would satisfy all fans.