People don't like it mainly because of how weak and "boring" it was. Ichigo's threat wasn't the destruction of his home or his world, but of his relationships with his friends. I liked that, it felt very different to what we were accustomed too. Plus Ichigo had lost all of his powers so Kubo had to have made some sort of arc in which he isn't at his best and there is still some sort of threat. When he was weakened by FGT, Kubo brought a group that would help him indirectly get his powers back.
Now Bleach is back to normal and people are complaining about how everything is the same..
