I watched the Trigun movie this morning (between 1AM and 3AM), and I liked what I saw. The main problems I had with it are endemic to all movies based on TV shows:
1) you have to had enjoyed it previously,
2) you have to have watched enough of the original show to understand how the characters relate, and
3) movie spin-offs are essentially a stand-alone feature-length episode.
Beyond that, it was great. Remember how the original animation quality was sort of faded and occasionally weak? This was excellent throughout...vibrant, sharp, yet everyone looked the same. Since the same studio did the movie and the series, there wasn't any jarring differences between the characters, though I think Vash's red overcoat had a lot of black on it this time. I may just not remember it being there, but it was a good contrast. It really looked good.
The four main characters--Vash, Wolfwood, Meryl, and Milly--were all there, but the insurance girls didn't figure very heavily at all here. The new characters introduced were pretty cool; Gasback, an older robber seeking revenge on those who betrayed him, was the standard big-guy Trigun enemy, but with a more interesting look than, say, the vast majority of the Gung-Ho Guns. Amelia, the female supposed bounty-hunter who serves as Vash's crush throughout, is another new character with one of the more predictable axes to grind in history.
The story...well, as I mentioned, it was an extended stand-alone episode, but that's okay. What I'm wondering is if it's supposed to have taken place within the original anime continuity, a new, singular one all it's own; or if it's more based on Trigun Maximum and heralding a potential new series? Given the original wasn't popular in Japan, I'd say no, but anything's possible these days, given the overwhelming quantity of tripe I've seen being fansubbed lately.
Bottom line: if you liked Trigun, you'll enjoy this movie. If you were meh towards it, you'll be meh yet again. If you hated the series, you need some LOVE AND PEACE.