There's a lot of humor. Nearly everything that anyone says and does is a set up for a joke... and I actually think that was too much. Like, the Sovereigns at the arcade. It's not bad to the point of ruining the movie, but when it's the entirety of the movie, it becomes mundane. At least it's not demeaning or too tasteless (except for the Sovereigns), and it knows to stop on the really big moments, so it's not a strike out. And hey, this "going too far" is still leagues better than going too far in the opposite direction that will destroy a movie much faster.
Everyone gets a massive focus, Yondu, Drax, Rocket are great, but Mantis is nonexistent (to the point I don't get why Gunn said he needed to give up adding Warlock to give Mantis some room, there's no room for her already), and Nebula is a bit weird, because the first movie simply showed her as this one-dimensional henchman fodder, and now they want us to care by revealing her tragic feelings. It's okay in this movie but as a whole it feels like how a character gets rebooted to get a fresh, better start. The complete opposite to that is Drax, where no one even says anything beside Mantis sensing that everything makes him laugh but then still extremely sad when haunted by memories of his daughter - the contrast with the first movie is enough to tell you everything about the weight that was lifted from him from Ronan's death and the weight that will never go away.
The family bickering was just so perfectly spot on. You completely get it from the first few minutes alone, long before Drax says it. In fact, most of the pivotal point for everyone is very cliché (Yondu being a father, Rocket, Drax, Nebula etc.) but it fits, it feels very natural (except for Nebula, as Drax would say). Well, Karen Gillian's acting made up for the Nebula thing.
Also last thing, the obsession from the Sovereign woman that completely flips out until the Adam cocoon reveal, kinda presented as the ultimate taboo she just broke like a mad scientist, that didn't feel warranted.
It's a great movie, but in a completely different way than the first one IMO. Guaranteed tearjerker. Also David Hasselhoff seriously.

The character work is so much improved that it's not even funny, the relatively small scale of the conflict keeps everything centered on the protagonists and their character arcs, and not only is the villain not an exceedingly disappointing afterthought, he's actually easily one of the best villains in the MCU! Like seriously, I think I might rate Ronan as the absolute worst MCU villain (only because it's such a squandering of the comics character; Malekith from Thor 2 is straight-up the worst villain in the MCU, but I'm less bothered by them screwing up that character), it was pretty shocking to see such a wild improvement.

Unfortunately, as in the first movie, Gamora is still absolutely squandered, with no real arc to speak of. She's once again a big ol' nothing of a character, who only exists to tell the other Guardians to stop being goofy and behave; She gets about 15 seconds of good (non-action/character-building dialogue) material after her fight with Nebula, but it gets passed over so quickly that it kinda just made me more frustrated; the rest of the time she's onscreen it's just in service to that dumb Star-Lord/Gamora relationship, which still doesn't work: there is no chemistry between these two characters, no actual reason why these two characters should get together besides the movie insisting that they should.Stop squandering Zoe Saldana!

Compare and contrast to Nebula, a character I had absolutely zero attachment to in the first GotG, and was not particularly enthused to see returning: in this movie, even as a relatively minor character, she finally received some sorely needed characterization that instantly made her compelling. And all it took was like, a 30 second, well-written monologue! Both Gamora and Nebula should've gotten that kind of treatment in the first movie!

Mantis (who is one of my favorite members of the GotG in the comics) had a pretty good amount of development for most of the movie, but I was really, really disappointed by the climax, where she basically became completely irrelevant to the proceedings. It felt as if her entire character arc had been abruptly ended: there wasn't a single moment in the movie devoted to the fact that she's essentially betraying her (adoptive) father, which is pretty weird cuz the movie's central theme is family? Ego is basically the only person she's known in her entire life, her decision to side with the Guardians is a titanic, earth-shattering choice for her. But the movie just sorta glosses over it; the movie desperately needed some kind of confrontation/conversation between Mantis and Ego in the finale, but instead she gets knocked out almost immediately.

Also related to the finale, I think it should've been reworked a bit. When the Sovereign show up, they sorta derail everything, but then they very quickly have all their ships blown up; the only thing they really accomplish is destroying the mining ship everyone's in. It just seems like it'd make a great deal more sense to have the finale be entirely about the Guardians versus Ego; he could blow up their ship, separate everyone, and I dunno, generate minions or something to give them a chance to have a cool fight. Maybe Mantis could use her powers to limit Ego's energy in some way, preventing him from using any big, overpowered attacks, and that's why he has to send minions or something? And then you could fit in a conversation between Mantis and Ego about her betrayal, and maybe also give her a chance to show off her sweet martial arts moves! But then ultimately she gets knocked out and Ego gets to use the entirety of his powers, and entraps everyone under rocks, as in the actual movie!

I think it would still be cool to have the Sovereign show up, but maybe they don't even manage to enter Ego's atmosphere? The movie never had Ego's giant planet face talk to anyone, and that's a HUGE DISAPPOINTMENT, because a giant talking planet face is amazing. So maybe the Sovereign could've still shown up during the finale, but while they're still in orbit, Ego (the planet) starts talking to them, and he blasts them all away? And that would still preserve the midcredits scene where Ayesha is in trouble with the High Council for wasting so many resources!