Bleach is basically Kingdom Hearts. The show has to consistently depower its main character and prevent him from ever achieving anything of merit. Also- darkness.
I would argue it's good all the way up to halfway through the arc after Soul Society. Spoilers for arcs after that:
Hueco Mundo: As soon as the Captains show up in Hueco Mundo it starts sucking. The Espada go from serious villains to Byakuya/kenpachi fodder. A competent writer would have had some of the supporting cast get meaningful wins (Chad, Ishida, etc.) But no, instead we gotta have them job. Also Ichigo's whole "let me cut off my leg" thing in the fight with Ulquiorra.
Fake Karakura Town: Just bland all around. The stuff with Gin is a high point but I'll never forgive Kubo for what he did to my man Starrk. #1 espada went out to a damn shikai. Goes on too long. The Aizen fight/final getsuga tensho itself is okay. Not how I would have done it but whatever.
Fullbringer: Actually this arc had lots of promise - like we might have actually gotten some character development for Chad. Also Riruka is best Bleach girl. But yeah, it falls apart pretty quickly.
1k year blood war: I truly truly hope the anime fixes this arc, because it starts off SO GOOD. Have Byakuya actually die, extend the final fight. We're rolling.