Yes, it's a serious comment. I know it's shocking that someone would dare step outside the echo chamber when it comes to that particular song, but you'll get over it. I don't like the song. To be honest, I hate it. I don't think it's the best song they ever did, I don't even think it's the best song on its album. I think Page did better guitar solos that get ZERO recognition, which is really sad.
Led Zeppelin did a great number of incredible songs I enjoy listening to. That song isn't one of them. It's not the end of the world, it's not an insult, it's not anything other than my personal opinion and feelings on that particular song. No more, no less. If you can't handle and/or accept that this is my opinion, and that at no time have I ever nor will I ever try to persuade people to change theirs, well.....that's not my problem. I shouldn't have to say I like something that I don't to avoid people like you getting your shorts in a knot about it.