I don't like them because they're blatant fetish fuel (I get it Clock, you want to be the fanservice race, but why make it so painfully obvious man?) and make no sense.  There is no single set of pheromones that you can attract every living species in existence with.  

Not to mention, the implications of being able to be "sexually attractive to anything because pheromones" means they probably also are sexually attractive to creatures that can't make spaceships including elephants, dinosaurs, insects, orangutans, whatever lives in Europa, really anything.  And they'd be able to make children with all of them...  Somehow.