Well I really liked seasons 1 to 3, although there were some plot holes, there was nothing major that put you off watching the show, in fact seasons 1-3 were quite enjoyable, and I was really looking forward to season 4. However, from the first 5 minutes of season 4 it was quite clear that something went wrong with the plot, indeed I can only guess that the script writers lost the plot, literally. Nothing that happened really made that much sense, and the story became very disjointed, confusing and at times patronising. I watched every episode of season 4, and it seemed to get a little better after episode 6, but still no where near as good as season 1-3. I lost count the number of times I asked myself, why would they do that, or can the Aliens be really that stupid ? I can only hope they sacked the season 4 script writers for the final season and hired people who can actually write a story that makes sense.