I saw the same showing that Switz did, at McClurg in Chicago. Very, very cool. The additions were seamless, and really should have been in the original release. There is nothing which is superflouous to this version at all.
My favorite addition is probably the “gift” sequence in Lothlorien, followed by the extended opening in the Shire. Lots of great humor added throughout, which really helped flesh out the characters, especially Merry and Pippin.
Thanks go out to all the people at New Line who decided to do this, it was much appreciated. I was hoping they’d have some “Two Towers” promo items to hand out, but no such luck. This showing was good enough of a gift, though.