I made it to the Friday night showing, with the director and lead character designer (neither of whom spoke any English)... there was a short Q&A with some very basic questions, and the audience was very excited. I wish I had thought to bring some of my DVDs to get signed.
The movie was like a lost episode, with a villain that looked a lot like Brilliant Dynamites Neon and a new chick that seemed pretty cool. There's a lot of slapstick (which only gets funnier in a room full fans;)), and the plot really wasn't that hard to follow even without subtitles. The animation was better than the average episode, which is great as Trigun's a bit dated now and always did suffer from some low-quality scenes. And it was great to see the old cast.
The director was asked if there were any plans to make a Trigun Maximum series, and (of course!) he said it depended on the enthusiasm of the fans here and in Japan.
I really never expected them to get a movie off the ground for this, let alone premiere it in the US; it happens SO rarely!