I think it would be useless to repeat all that the other users have said about "Threads" since I cannot do better but agree with everything. This has to be THE most graphic representation of nuclear war. And I used to think "The Day After" was disturbing.
I was able to cope to the whole movie, but let's say it wasn't easy at all. I can still hear in my head the yells of the panicked citizens as the mushroom cloud rises in the distance when it hits Crewe... or see the bottles of milk... or the corpse (which bears a striking resemblance with E.T.!) burning in the firestorm... or see survivors keeping as gold what is taken nowadays as granted: supermarket plastic bags... and what they put inside is simply disgusting.
When I found out my local video store had a copy of this film, I rushed to get it, as I was impatient to see this movie I have heard so much about. The impatience to see the movie was rewarded by nothing more than a really bad aftertaste of radioactive fallout.
I liked the movie not for the quality of the actors, but for the overall realistic representation of the holocaust and for the great job done with a small budget. I give a thumbs up to that.