I didn't really think that about Pulp Fiction, which is one of my favorite movies. But his next movie, Jackie Brown, is the first of his movies where I noticed he really needs someone to rein him in. That movie just drags. And Death Proof is a serious contender for the most boring movie ever made.
I was really disappointed with Once Upon a Time in Hollywood. Tarantino seems more interested in how the movie looks rather than telling a good story. It all seems to have no point other than to just set up the ending which is a bizarre mix of slapstick humor and horrible violence.