Gravity falls is a great show but lets be honest the ending didnt live up to the hype. The symbols cercle to stop bill was such stupid idea that didnt make any sense even by gravity falls standards. The stan twin swap was sooooo predictable. And for Bill he was such wasted potentiel. He got so little screen time when he is not with one of the pines.
He was introduced as a very knowledgable and insane creature. Hell he even told ford how to build the portal. Later he seamsed so clueless about what stoping him from going worldwide. Also It was stupid to give bill friends too. It made no sense. I think everyone was expecting some kind of backstory for bill existance and a lot more screen time of him having his own adventures or messing up with things in other dimensions without resorting to his usual lying.