Dave is truly one of the true gems of this show, in my opinion. Many people would disagree, but to me this episode was just a huge mindtrip.
Alot say that they seen Dave not being real from the first minute. Well I didn't... so having it revealed that Dave is Hurley's imaginery friend in the middle of the episode really shocked me. Simply put, this episode explained every single mystery by claiming it's all in Hurley's head. And how funny; it all makes sense. While it's not the case, iT'll make you think think and think even more. It was just really well done. I was ready to get a happy ending with Libby kissing Hurley, but then we get a Libby flashback sequence only to find out she was in the same mental hospital as Hurley. And she seemed somewhat dodgy too. What?
The subplot, with Sayid and Ana trying to get info out of Henry wasn't very revealing but it was exciting so to say. But I just couldn't care because I was so invested in Hurley's super freaky storyline. It creeped me out even more than Numbers!
OVerall, can't quite rate it perfect on the basis it's still a filler episode no matter how amazing it was. Plus there definitely was room for improvement dialouge wise, but I'll look past that for now.