Mulholland Drive

Can someone please explain Mulholland Drive to me? I know it’s supposed to be brilliant as it was written and directed by David Lynch but the movie is a mess –at least the last 30-40 minutes. Oh sure if you are in to girl on girl action, then its hot and engrossing, but there is no logic to how things ended. So I seek an explanation. It’s almost like he’s playing a joke on us (or at least me). I just don’t get it.