I'm a huge Firefly fan but I will admit that it wasn't until Mrs Reynolds that the show clicked for me. I think Joss said it had higher ratings than Buffy did during her first season but presumably sci fi shows require bigger budgets so they expect more.
It took me far less time to warm to the characters than it did on TNG (although River was a bit too slow to develop I understand that her development was intended to be a running theme) and the stories were of much higher quality. The movie is one of my top ten sci fi movies.
I think the show could have picked up enough momentum to be great. I would have loved another 13 episodes to round out his season two plans but as it is I think it stands up pretty well.