I'm avoiding direct spoilers, but let's put it this way. When the series started, a lot of people had the reaction that the premise was kind of sick and weird. By the time you get through Epitaph One (the unaired episode), it's really clear that the whole point of the series is that there is no "kind of": when you carry the idea through logically, the results are horrifying. It's classic science fiction: take one idea (in this case, the notion of being able to record human minds and imprint them on others), and see where it goes. The show is unflinching, both in showing why the concept is alluring, and just how dangerous it can be.
It's now on DVD (the only way to get the original pilot and extra episode), and IMO is worth watching that way. Like all Joss shows, it builds in momentum over the course of the season. I strongly recommend *not* watching the unaired pilot until you've watched the season: for a change, I think the network's decision to demand a better pilot was correct. The original pilot gives a great deal away very quickly, whereas the season as aired lets the secrets play out much more gradually. (And Epitaph One goes at the end, as an epilogue to the first season and a hint of things to come...)