I'm not going to write a treatise on the show. There's been plenty of virtual ink spilled already about the show, and I don't think I'm going to really add anything much to the discussion that hasn't already been said.
What I will say is that the series was great. Perfect? No, of course not. There were a few too many coincidences for me that led to things happening (I suppose in something this complex that must be inevitable) and some over the top ridiculousness that pulled me from the series because of how surreal it got. For any who have seen it, the end of season four would be a prime example. Yes, it was satisfying as hell, but realistic? Hardly.
Some questions remain, which I also suppose is inevitable. It's a lesson in writing - not EVERYTHING needs to be wrapped up with a neat bow, though that was something I learned earlier from Lost and The Sopranos. That said, this was one of the more satisfying season conclusions I've seen. We found out what happened to most of the main characters (one of them is a bit ambivalent) in a way that left me not feeling as though there was more story to tell.
That said, I felt like the series was a long movie - a very long movie - in a way I've never seen before on tv. It was certainly worth watching, and one I will recommend to anyone looking for a gripping drama to invest some time in.