I think Baymax is a pretty cool character that kids are going to go gaga for and I love the way the film played with his materials. I think San Fransokyo is pretty inspired. The fractal electron microscope cloud world through the vortex was gorgeous looking.
... but that's pretty much it. The Big Hero squad are barely integrated into the film, except TJ Miller who plays the same dumb wisecrack character every animated kids movie has and really didn't earn the screentime he had. I have no idea if that's a remnant from a draft of the film where his character had a bigger role (the rock trolls in Frozen were a leftover from an earlier draft) or if they grafted him on to make the movie funnier or have another human character. We see very little of the city except for the flying sequence which is short and not super interesting. The plot is threadbare and literally dumping the exposition into five seconds of "Wait, the dead pilot is his daughter??? And now he wants revenge????" sucks. Also the film really had almost no emotion. Baymax's sacrifice was so obviously not going to stick and nothing else really registered emotionally at all.
The whole time I was watching it I was thinking "wow this is clearly being made for 10-12 year old boys" in a way that I haven't seen since, uh, Cars I guess? I have no idea what the comics are like but this was obviously made as part of the cradle-to-the-grave marvel fan machine. They have a formula, and they aren't afraid to use it. The post-credit sequence was embarrassing because it took the worst character of the movie, stuck him in with perennial comic fan in-joke cameo Stan Lee, and made a stupid teaser. It's such a vapid practice in the Marvel films, disappointing to see it here.
It doesn't drag as much as Wreck-it Ralph--
which I was pretty meh on, and it's not as boring or empty as some of Disney's worst like Home on the Range, but I didn't think it was a good movie. I'd give it a marginal thumbs down or marginal thumbs up, definitely not a strong recommendation either way.