Well, I would say that if millions of people have enjoyed and found value in opera (or any other art form for that matter) over a period three or four centuries and even more millions of people continue to find enjoyment and value in it, for someone to ask "Is opera rubbish" is less a thirst for knowledge than a display of abysmal ignorance. Even if someone absolutely hates it, it's pretty stupid to say that it's "rubbish." To some benighted people, just about anything you can name that people find value in is "rubbish." It tells you more about the person making the remark or asking the question than it does about opera or whatever.

Sorry, jOhn from Hull, but if you don't know or understand something, that doesn't make it rubbish, it just means you don't understand it. If you do understand it but don't like it, that's okay. But that still doesn't make it rubbish, it just means that you don't like it.   

Don Firth