I like to call Bleach one of the founding fathers of my anime/ manga experience, up there with Naruto and One Piece. These 3 classics are what got me into the world of manga in the first place.
Bleach may appear as a cliched shounen manga type that we see today, but you have to remember that it contributed to the standard of shounen manga that we see today.
The characters, both good and bad, are well designed and given enough depth that we can see what both sides are fighting for as justifiable and reasonable from their point of views. While it may be one of the longer series out there, it has good reason to be. The arcs are of a good length and are well structured unlike the fillers we see in the anime.
Even if it may appear as generic and unoriginal on the surface, it established a foundation of what shounen manga is for me, earning it the rating I've given.