The plot is weak, but I suppose you don't go to see movies like these for their plot. There is a twist, and that is that Godzilla is pregnant, so even if you kill him, there are more waiting. The special effects are amazing, but to be honest, after all these special effects dominated movies, it just didn't feel that special anymore. The huge lizard thing was done to perfection in Jurassic Park, and the blowing up of buildings in New York was done in Independence Day. Some of the chase scenes were done very well, and all the baby Godzilla's in their nesting area were quite good. There just wasn't that awe that you felt the first time a dinosaur walked across the screen in Jurassic Park. You can predict everything that is going to happen, there are no more surprises. The scenes of the helicopters chasing Godzilla through the streets of New York were exciting, but the scenery didn't look anything like New York, unless you consider the King Kong ride at Universal Studios. The acting was just acting, nothing all that special. I do love Jean Reno as an actor though, I haven't seen him do a bad role yet.
Overall, I'd go see Godzilla if only for the hype surrounding it, but don't go in expecting anything new, because you've seen it all before.