Ditto. And I only watched Firefly after Serenity.
Same for my non-geek friend, who thought the film was terrific and still hasn't watched the series (though he bought it).
I think Serenity gave the SF film a fillip, much as the orginal Star Wars changed the general public's opinion of SF in general (oh, it can be just Space Opera! with the "technology" just magic bits to impel the plot); so too the whole re-focusing of extra-solar exploration paradigmatically with previous forays by individuals into uncivilized and dangerous wilds / badlands (the US after the civil war, for example, but also many others) gives new purpose and (more importantly) new meaning to the old tales of space travel. It is easy to die in the middle of the ocean from a lack of water, after all.
Now SF doesn't have to be robots and lasers doing the deus ex machina denoument, it can be regular fiction with regular characters dealing with an unfamiliar (to us) reality: "You live on a space ship, dear."