Spoiler-free summary: BIG ROBOT SMASH BIG ROBOT! BIG LIZARD SMASH BIG CITY! SMASH! SMASH! SMASH! WHEEAAALAAALAAAAGH!
Seriously though, those who liked the first one can probably find things to like about this one; the movie barrels along at a frenetic pace, not letting itself be too troubled with things like "plot" or "plausibility". There are worse ways to spend two hours.