It was a James Gunn movie more than a Superman movie, but that's OK, I suppose. Superman was never a super interesting character. It's kinda nice that they showed him capable of being vulnerable, even when the kryptonite wasn't out. That helps him tremendously; that's always been my biggest beef with Superman as a character. The only way to challenge him is to give him moral dilemmas or threaten his friends. It gets old. That said; he was occasionally kind of rash and impatient, which isn't Superman. Showing up to threaten Lex wasn't cool. The Whedonesque dialog was toned down to manageable levels, I suppose, although it was still occasionally eye-rolling. That said, I read one review that called his a terrible Superman movie but a pretty good Clark Kent movie. I can kind of see that.
Krypto was OK. A bit over-used. Nice that he'll (presumably) be gone now from whatever franchise emerges from this. Guy Gardner was just there for the jokes. Mr. Terrific was, actually, kinda terrific. Surprising, because he's never been an A-lister, to my knowledge. Not that I'm a huge DC guy. I guess that's kind of the James Gunn MO though.
Not being a huge DC guy helped. I recognized but wasn't offended necessarily by the big changes in character of the Kents (super bupkiss), his Kryptonian parents (super Genghis Khan) and Supergirl (Supertramp), because I'm not invested enough in their default versions. Not sure why any of those changes needed to be done, though. The Partygirl cameo at least made me chuckle.
The credit scenes were both a waste of time. I feel like the plot was serviceable, but hardly exceptional. No surprises at all.