I wanted to like it, and there have been far worse episodes, but that whole "protect the light" thing just came off as extremely corny to me. As James pointed out, some things were answered, but, once again, this led to even more questions!!!
I have read elsewhere that this was just a useless filler, but i actually liked the part where they showed the first time Jack, Kate, and Locke were at the caves. It cleared things up for those (me ) who really couldn't recall that scene entirely. Wasn't that in Season 1?
I wish they would just give MiB a name already! Anyone notice the "Island Woman" (give her a name too!) and her speech about people? Verbatim to that of MiB's on the beach in the S5 finale. "They fight, they destroy, they corrupt, etc." There is so much more to this MiB and Jacob story that I want to know about.