First two series were outstanding, season 3 they were milking it, season 4 had its moments but was a bit muddled together but had its moments. I now hear that season 5 is set in Germany. So season 4 and 5 have nothing to do with the original concept, moreover just a platform for Carrie the fire starter Whom in reality I'd have expected to of been taken out of field service if not the service entirely, i.e. its gone a bit too far fetched, they should have stopped at the end of series 2.
http://en.wikipedia.org/wiki/Homeland_%28TV_series%29