since it was canceled way too soon, as fanboys say, is the end going to piss me off?
Not really. They were notified before filming the last episode or two that they were canceled, so there were no huge cliffhangers. They wrapped stuff up decently. What they didn't wrap up in the show got wrapped up in the movie.
And yes, if there's anything that pisses you off, it's probably going to be the movie follow-up, Serenity.
A note about watching the show: Watch the episode (not the movie) Serenity first, followed by the Train Job. The rest should be in order. (Ah, good. Netflix has them in the correct order.) Stupid execs and their forcing a refilming of the pilot, making things more confusing than it needed to be.