1) Glad to see the big G is taking an interest here.
2) Definitely bummed that it's US only, prior to seeing that post I was already assuming that that is a temporary thing, but in the short term it's kept me from spending much time playing with it.
3) The UI work looks very nice and in keeping with Google style, even so. I'll definitely check it out more when my next plans are for US travel rather than international.
4) For the hardcore folks here, the ITA Matrix interface will probably always make more sense - although some way to get it (or a prettified but equally functional version of it) from the flights page would be nice.