It is perfect in every way.
Wash dying is sad, but it gave it the air of drama it needed. Too many films give characters that "untouchable" feel where you know they're all going to be okay. That last stand scene, where one by one they all drop... knowing that Wash and Book have both been killed makes it plausible that they might not get back up again.
One of the things about Serenity is that, to draw a metaphor, it's Return of the Jedi. The series is Eps IV and V, the film is VI*. Because Joss knew he wasn't guaranteed another film afterwards (because he was hella lucky to even get one), he gave it a sense of closure. There's scope for more if needs be, but Serenity tied pretty much everything up and gave some form of response to [most of] the lingering questions from the series.
It's also quality on its own. Hell, even Jonathan Ross loved it. Said it had absolutely everything that was missing from the last three SW movies.
Yay, another convert.
* - And the events of Eps I-III get covered in flashback throughout the series. Everybody knows Mal & Zoe: Teh Early Years would be rubbish. Because we all know how it ends.
[EDITAGE]
The Official Serenity Thread:
http://transfans.tfarchive3.com/phpBB2/ ... php?t=4245
Star Wars Deathmatch:
http://transfans.tfarchive3.com/phpBB2/ ... php?t=4431
Puppets!:
http://transfans.tfarchive3.com/phpBB2/ ... php?t=4574Grrr. Argh.