The reason the silver surfer help galactus in sucking the life planet is because silver surfer came into deal with galactus to spare his planet from being destroyed and subsequently saving his love, Shalla Bal. Enough story telling and move on the movie. Like other comic adaptation movie, its a dissappointment. They try to cramp a whole lot of plot in one line of story. There's a several missing links but still acceptable since the main story line is there. Haih another plot think on your own or go read the comic.
The special effects is nice except for the opening where they try to show silver surfer travels to the earth. Its looks fake...note to director "try to work harder and make it look like real wouldn't hurt". Jessica Alba acting are still...how should i say...unnatural. She doesn't really know the character. Another disappointment. The ending are left hanging...a hint there would be another sequel and it suppose to be better? I doubt it.
My verdict : 3 1/2 out of 5