I went to see this film on Friday evening. I also recently watched the 2005 version again to remind myself of the first F4 film I've watched. I didn't think the 2005 version was awful, just that it was more of a child's movie. The new 2015 version does some things better and some things worse. Overall, I don't think it is up to the standard of other recent Marvel films. The ending was weak and the whole film felt as if it had been mercilessly butchered in the editing. It was mercifully short.
I thought the relationship between Reed and Ben was set up well in the first half but then it went downhill. Victor von Doom wasn't very strong as a human character, he had more going for him after returning from the other dimension. There were parts that felt truly scary but the sense of fear and dread was not sustained. The idea of Susan Storm as a step-sister of Johnny was cool but not very believable. I also didn't think much of the jealousy exhibited by Victor for Susan when she showed interest in Reed.
Overall, this wasn't a terrible film, it was just underwhelming but perhaps it is a victim of high expectations after the Iron Man, X-Men and Avengers films.