I participated in closed beta testing, too. It was truly awesome. A bit too arcade-ish for me, but that's just a matter of taste - nothing a realism mod won't fix.
I wrote a detailed account
here, and uploaded some screenies, for those interested.
As a side note, I just
learned that I'll receive
a piece of the Berlin Wall if I buy the Collector's Edition
. There's a smart marketing ploy if I ever saw one.
As for expansion pack countries, I'd go for the Warsaw Pact nations and the People's Republic of China.