I read it about 30 years ago and liked it. If you’re half through with it, it’s not going to get better for you. Like others have said, it’s not for everyone.
Recently, I've been reading "Tomorrow, when the war began", which is basically Australia's Red Dawn. The synopsis is quite similar. A group of young people return from a camping trip to find out Australia has been invaded by "A Coalition of Asian Nations" who have decided that Australia must "share" their land.
They made a film about it which is on youtube in it's entirety:
If you like and watch all the Dr. Who series, especially the old ones, you'll probably be a Hitchhiker's Guide fan. HHG definitely wouldn't make a good read for most people, same with the movie, but most people hate Monty Python too.
I did not care for American Psycho either. It was alright but nothing I would want to read again. On the other hand I am re-reading my favorite adult werewolf series for about the 6th time. None of that weird hollywood crap, blood thirsty monsters, or teen drama BS. Just a good story that follows a guy who just happens to be a were from before WW1 until he dies in the 80s I believe.
I loved the books, thought they were as funny as anything I've ever read, its probably been 15 or 20 years ago. I thought the movie was ok, thought the books were great.