This was a great fucking episode, possibly the best of the season. Loved seeing Alex, and she was so pretty! Somehow she really looks like Rousseau to me, too, but in a non-"standard TV" way - excellent casting.
So many excellent creepy touches - the airplane mobile (I get chills again just remembering it), the broken fluorescent light (although supposedly the power was off - whatever, la la la, hand-waving sense for atmospherics), Ethan sounding all nice, friendly and rational. Overall the flashbacks were really well done IMHO. Loved poor deluded Claire shouting for Ethan like he was her best friend.
I don't trust Libby at all - she just rings all kind of alarm bells for me. I don't know how much of that is from the washing machine scene, and it may be a huge misdirect for Hurley in the asylum (speculation, not spoiler), but something about her just pings me all wrong.
I'm also convinced Henry is an Other - which probably means he'll be a red herring too, but that's okay if they do it well.
ETA, psst, quester - your tag has a typo