The monsters all look silly. I wish there was an option in the games options to play with monsters that don't look like they are from a childs coloring book. For a game that millions of people are going to pay millions of dollars to play for endless hours it should have really good art (the background art is unimpressive!)
I quite like the monster designs. Starbound is a cartoony game and the designs fit the feel of the game overall. Trying to smash things you consider "cool" into a game where they don't belong is the easiest way to make an incoherent mess.