I read somewhere on the net that Firefly was a really good new SciFi series so I checked it out.
Unfortunately it's not SciFi at all. What makes a SciFi story SciFi is some new technology, phenomenon or discovery and what its repercussions are. Examples: What if time travel exists? Could you go back and stop your own birth? What if teleporters exist? Would cities become depopulated since you could live anywhere? What would change if computers or robots became sentient. Would they take over? What if we met Aliens? Would they have similar beliefs? What if a replicator existed removing the need to work? Would people do greater things our all become lazy?
Firefly has none of those types of ideas. Instead the issues covered could just as well be set on a pirate ship in the 1400s or a bunch of horse riders in the 1800s. I'm not saying Firefly is bad, it's well made, but it's not SciFi.