Saw this last night. It has its flaws, mostly in what at times feels like some rushed plotting, but overall I thoroughly enjoyed it. Brolin is excellent as Thanos (unlike the comics, he's not just a demented nihilist, he actually believes what he's doing is for good of the universe) and the mo-cap and CGI capture every little flicker of nuance and emotion that crosses his face. Seriously, I could watch an entire movie consisting solely of Thanos' head, they do that great a job with it. I'll avoid spoilers (of course) but suffice to say, when Gamora comments at one point that with the gauntlet Thanos could kill off half the universe with a snap of his fingers, she's not exaggerating. And let me tell ya, the Gauntlet isn't picky at all about who it spares and who it wipes out. Also, there are a number of cameos, none of which I'm going to spoil here.
Well, okay, just this one because I can't help myself...
Spoiler...
RED FREAKIN' SKULL!!! Skull's always been one of my favorite villains and I enjoyed the hell out of Hugo Weaving's performance in TFA, so seeing him again brought a massive smile to my face. But it was bittersweet; I loved seeing the character return, but it wasn't Hugo Weaving playing him. It was Ross Marquand, aka Aaron from The Walking Dead. And while they did a good job making the face look like Weaving in TFA, Marquand missed Weaving's Werner Herzog-inspired accent by a country mile. Oddly, when the character first appears, I actually thought it was Lady Death. You'll see what I mean when you watch it.
My only real complaints aside from the plotting are that, while there is plenty of humor, some of the jokes fall flat. And as there are at least triple the amount of characters here than were in Civil War, there simply isn't enough screen time to fully service them all (which ties in to my comment about the plotting feeling rushed). That said, when the movie does decide to get deep or dark or emotional, it really leans into it. The ending in particular had me choke up a couple of times.
Overall, this is solid entertainment and I doubt MCU fans will be disappointed. Top-notch effects, massive set-pieces, and the Russos thankfully have no problem going full-on comic book, delivering scenes and images that old-school nerds like me who grew upon comics thought we would never see on a movie screen. It goes without saying all the performers have their characters down pat, and the Russos' vibrant visual style is on full display. As for whether or not Avengers 4 will be a continuation, considering how this movie ends and knowing what MCU movies are on the slate between now and when Avengers 4 comes out next year, it pretty much HAS to be. 7/10