I don't hate it
but I find it annoyingly extraneous. I didn't care for the flashbacks (added nothing), I didn't care about that new "bad guy" Jesse had to go have a showdown with (yeah, sure, Gilligan is going to let Jesse survive the last BrBa episode and then have some lamewad kill him in the movie, YEAH, such tension here!), and I didn't like that the final scene just confirmed what most fans figure would happen to Jesse anyway.
It wasn't painful to watch but we hardly needed it; all I'm ever going to take from it (aside from a rather awesome trailer that REALLY made me want to see it) is a few nice scenes with fat ol' Jesse Plemons.
"Most" big fans is not "all" big fans--I adore BrBa. But now if Alpha Hammer were to come back I bet he wouldn't like it much either.