Can I unsubscribe from iTunes Match?

It is an annual subscirption, so you could simply not renew when the year is up.

Otherwise, you will need to use the express lane help section under the support tab, and put in a support ticket with the iTunes store asking to unsubscribe.

https://expresslane.apple.com/Issues.action

I relly like iTunes, however, I think I'm giving up on Match... iTunes Match is replacing graphics (artworks) and metadata as it see's fit, and it's quite annoying. I'm not willing to keep spending hours organizing my iTunes library anymore. I've spent hours organizing my library, searching and placing artworks and data and iTunes Match basically screws all this up! I realized I never expect to get video purchases on my iPhone or iPad anymore. Same thing about covers/artworks... Perhaps, iTunes Match is the worst Apple product in years... Good bye, Match.

You are certainly free to feel however you wish about iTunes Match, but resurrecting two-year-old threads created by other users just to complain is inappropriate. If you want to comment to Apple, use their feedback page:

http://www.apple.com/feedback/itunesapp.html

I really appreciate your response and suggestions, thank you. Sure, I already sent my comments to Apple and I hope they fix iTunes Match before within 2 years... By the way, what is truly inappropriate is that after 2 years in the market iTunes Match stills presenting exactly the same problems... No resurrection because Match's failures have never died. I'm just asking for a little respect for customers time and money...