way too long, no focus, you mention "I" too many times when it's a complaint of the movie theater, I had no idea on what you're talking about by reading the first paragraph (the intro should state your problem), you didn't make a demand (don't ask, demand) of what you expect them to do about the issue, and it seems that you've already made the decision to use your home theater instead of a movie theater - why should he care what you have to say then?
I'm not trying to be harsh but if you want something more powerful then there's no use in sugarcoating it.
Also, try bunching up your thoughts. You go from to your statement of problems to what it used to be to about films in general to statement of problems to another problem to not being a whiny geek to comparing it to your home theater to a link with no real description to what you're linking to, to restatement of problems, to what you would like, to ... blah, i can't go on.
edit: and if it's to the manager of the theater, do not put "to whom it may concern". put in the manager's name.