I thought it was an amazing episode. The "who is Jacob" (partial) revelation brought back memories of how I reacted to "what's in the hatch?", "what did Kate do?", "what is the monster?", and "how did Locke end up in a wheelchair?" - and that is by being nothing like what you'd ever suspect, but being nonetheless awesome. Those were all moments that could become anticlimactic but yet again, the show didn't disappoint.
Jacob looks like Alvar Hanso.
Oh, and no way Locke dies. No way. I don't want to even semi-believe it. He's too important a character to the show, and if Locke ever does die before the series is out, Damon and Carlton would give him a much better send-off than that. He deserves a much better send-off.