Until a credit card error combined with an email filing error caused me to miss several issues in a row (and I was already months behind on actually reading them even then), I collected Buffy and Angel comics set after those shows had ended. In addition to those, a handful of Firefly comics were released, but these were not of the full-sized sequel variety the others had been. A three issue follow-up story with only one spoiler of any consequence, and a second batch about which I, perhaps tragically, remember nothing (but it was past stories instead of future), and then by the time the third set happened, I had already had the card failure of which I speak, I guess?
Leaves on the Wind is not only the fourth collection; it is also, finally, a full-fledged continuation of the story with (I believe) more to come. In addition to the fruits of that spoiler I mentioned, mostly this one is about the fallout of the big revelations broadcast by Malcolm Reynolds about the Reavers and how they relate to the Alliance; you know, the ground covered in the movie. There are people who don’t believe a word of it, people ready to start a whole new revolution, people looking for all kinds of bloody revenge. You know, the usual.
Definitely worth reading, but read Those Left Behind first.