Bendis is not the worst writer; dude has done some stuff that I really like (Powers, Jinx, Torso, Ultimate Spiderman, Miles Morales Spidey) but he also is a bad fit for certain kinds of books/characters resulting in him doing some really bad work (Avengers, Guardians of the Galaxy, his X-books).
Hopefully being at DC will renew his writing skills since being at one company for so long can only result in a bit of stagnation but he and DC need to put him on books that his style would be a good fit on. Stuff like one of the Batman books, Green Arrow, Batwoman. But keep him away from team books especially Justice League because that would be so bad. Also they will hopefully not to have free reign on company wide crossovers.
Of course even when he has been terrible his stuff has sold like gangbusters so we should probably expect him to write solo books for Batman, Wonder Woman and Superman plus be the new writer on Justice League while pumping out yearly mega-event crossovers.