So far my experience with iTunes Match has been horrible. I keep getting a ton of unmatched songs that absolutely should be matched, and lots of upload errors.
For example, the album "Houses of the Holy" by Led Zeppelin.... http://i.imgur.com/RscRg.png
After toying around with it for a while, i found that sometimes using iTunes to create an AAC version of a unmatched song, the newly created AAC version does get matched. Not sure why this is, as the original unmatched files are 320bit MP3s.
Another issue I've found is that albums are not sorting correctly on my iPhone with iTunes Match active. I use dougscripts in iTunes to copy the release year of all my albums into the "sort album" meta data field. So that way on my ipod or iphone albums are sorted chronologically. Through iTunes match, none of my albums are being sorted correctly. Its not even that they're sorted alphabetically instead of chronologically. They're just listen in what seems like a completely random order.
Yet another MAAAJJJOOORRR complaint is with the album art. I am very meticulous about my album art. Every album in my library has album art displayed. My first step in getting album art is trying to get album art through iTunes. Most of the time this works fine. For the ones that dont, I just search google images and copy and paste the album art in... What I'm finding though, is that all my albums with album art gotten through iTunes, is not showing up on my iPhone when using iTunes Match. But albums where I had to paste a image in to iTunes, those do show up on my iPhone. This is not 100% consistent, but pretty close.
Overall I am very disappointed with iTunes Match so far. The Apple philosophy of "it just works" certainly does not apply to this product.
Im going to wait it out another couple of days or a week or so, and if things don't get better, I'll be calling in asking for a refund.