Meh.
I didn't have high expectations of this film, and it met them.
I didn't have a problem with them changing Galactus, but I think that if they were going to take the obvious clues from the Ultimate Gah Lak Tus version (I noticed at least one line they just took out of those comics, the 'quarterback' exchange between Reed and General Idiot, except it was better in the comic. Why yes, I am a colossal geek), they could have gone the whole way. In the Ultimate version it's a massive cloud of mechanical drones, which all had the Galactus helmet design. Here, it was just a cloud. I did see the helmet shape in the bit at the end, but I was expecting to, so maybe it's like trying to see a shape in the clouds. The people who know what it is will see it, others won't even notice a shape at all.
It's an improvement over a giant man in purple armour, anyway. I think people would have just laughed at it if it had been the 'classic' Galactus, it's be like the old B-Movies where the space alien is just a giant grasshopper.
The Surfer was well done, though.