Serenity was great, I really, really did enjoy it. Worth the lone trek to the cinema to see it.
Firefly... just didn't seem to gel for me. I liked the premise, the characters, the stories, but something was just lacking.
I'm really not sure what it was. The movie felt like a real fun ride, I guess it had to be since it was make or break for a continuation of the series, or a last gasp, I can't remember which. But the tv show just seemed to sit around, bask in how cool it was sure that it was and didn't go anywhere.
My own opinion of course, not the prevailing one on the internet for sure