(I'm not promising there won't be spoilers here)
I was going to wait until next weekend to see it, but after hearing about how badly it was doing I wanted to go see and make up my own mind about it before I heard too much about it; which is what I just did.
There weren't many people in the theater, there were more in Ant-Man on its second Sunday( they did have lots of showings today for F4 and only had 2 for Ant-Man when I went) And as far as I can tell there is a lot of people saying it sucks that haven't seen it.
I really don't have any major issues with it that I don't already have with most movies of this type. The effects were mostly great, and story wise there has been far worse.
I think what may ruin it for most people is the super heavy emphasis placed on the origin story. It's almost all origin story with a sudden, out of nowhere crisis. It's like 80% origin story, and 20% actual crisis which made for a very compressed feeling crisis and ending. Usually it's the other way around, but I actually really liked the time taken on the characters. I wasn't bored, and it was nice to not feel rushed through the evolution process. On the flip side that came with a price, because to finish telling the story the way it starts the movie needed to be much longer - like almost an hour longer. People don't like long movies, and I'm sure studios wouldn't like like funding them. In the end the crisis was short, senseless, and we don't have any real perspective on why Doom is Doom bringing doom.
If I'm going to be critical I do think they needed to do a better job showing how Sue ended up getting her powers. They showed some of the others getting "attacked" (if you will) by things resembling their powers, so all they really needed to do was show something hitching a ride in the empty pod and go get her. I think that would have been enough, or something at least.
Planet "Unexplained Magic" aside, my main beef though would be the chronic need for these superhero's to be saving the planet every time. I mean, dude, can't four kids just save something less extreme than the planet on their first outing? What do you have left to save now? The planet? Again? The fact that it all happened in like 15 mins didn't help but marginalize the gravity of what saving a planet should be. It's going to really suck to be a human on the day one of these heroes fails to stop a bad guy with a shallow, contrived need to vaporize everything.
But that is a criticism of story trends, and while it's definitely a problem for me here, it's not really a unique problem. Overall, I thought it was just fine, and would watch it again.