Godzilla was disappointing. They could have had a little more screen time with monsters fighting. The lack of Godzilla wouldn't be as big a deal if Aaron Taylor-Johnson (Kick Ass) didn't have fewer facial expressions than the monsters. Either he was just horrible as the lead (seriously, Arnold from T2 was more human than him), or the lead part wasn't scripted well.
If you want a giant-monster movie, it teases and teases then doesn't deliver. If you want a good story, this one falls flat on its face about 30 minutes in after a certain major event I will not spoil because we don't have spoiler tags.