He started out cute enough (if not at all my type) but SUCH A HORRIBLE PERSON (he's got good qualities, but there are too many moments that make me furious at him for me to really love him)

I'd argue he starts out as a 'typical' teenage boy, as befits his intended everyman status. YMMV, of course, on whether it's intentional that the average teenage guy is a horrible person when it comes to dealing with girls.