After being solely dedicated to 2-channel listening for nearly 20 years, I started an HT system with components I had kept from my audio system.
I realize that many people do not have the luxury to set up a system in on room for music and another for movies. But in the context of many homes with a TV/Movie setup in a family room setting and a basement room to set up a dedicated music system, it can be wonderful. And I must admit that it is very nice to have surround sound for so many movies.
Yes, it does make a huge difference with a lot of movies with special effects. For other movies where this is not the case, I would agree with the above posts.
Ultimately if I only had one room for all this, I would focus my attention and resources to the front 2 channels and start with a budget amp and speakers for the surround.