Also note that you will no longer be able to sync audio and video content (except for movies, apps, and photos) to your iPod using your computer and iTunes. Your entire music and music video library will be taken over by iTunes Match. You can't have both, you will need to choose to either just sync with your computer and iTunes or sync with iCloud and iTunes Match. It really is a messed up system at this point especially since you will forever need to be connected to a wi-fi network with your iPod if you want to listen to new content.
On top of that, iTunes Match may or may not be able to actually match your content with stuff already on the iTunes Store. I have had multiple issues with this even though I know the content is on the iTunes Store. I am not sure what is going on. For example, I purchased Korn's new CD. I ripped it with my Mac, imported the files into iTunes, and iTunes Match scanned them. It was able to match 5 songs total, it had to upload the others. The album has been on the iTunes Store for a while now yet iTunes Match kind of gave up. So not all of your music will be upgraded. iTunes Match will upload a file to Apple's servers when it cannot find a match. So things aren't perfect with that aspect. They are better than I thought they were going to be in some areas but the service is still finicky at this point and, unless you really, really, really want an online backup, I suggest holding off on the service until Apple irons out the bugs. iTunes Match should not have been released in its current state. I think Apple rushed things out the door since they missed their self-imposed October deadline. I would rather have had them keep developing and wait until the new year.
64GB iPhone 5 | 64GB iPad mini | AppleTV 2 (2012) | AppleTV 2 (2010) | 4GB 3G iPod shuffle | 2012 15" MacBook Pro, 1TB SSHD, 16GB DDR3 1600 MHz, OS X 10.8.4 Mountain Lion | Apple Lossless | iTunes AAC -Q 68 | iTunes 11.1 | Library size = 1.78TB | Legacy iPods: 3G 40GB, 4G 40GB, 5G 60GB, 160GB iPod classic (2009)