Several podcasts and news feeds I partake of have been talking about perceived problems with iTunes Match. My experience has been pleasant. My first attempt to enable iTunes Match told me it was not available. I waited 5 minutes and tried again and was successfully activated. The "upload" took a couple hours. I have a moderate sized library of less than 40K tracks. I have some odd-ball stuff like Henry Rollins spoken word performances as well as video game and movie soundtracks. At least 95% of my library was matched (not the Rollins stuff)
I've heard concerns that people are being enticed into a new form of "DRM" with iTunes Match (Episode 371 of Tech News Today). That seems like artificial devil's-advocate kind of B.S. If you have a backup of your iTunes library, then you still own the originals. If you don't have a backup then you don't really care about your library anyway.
I've also seen complaints about the $25 price tag. That's just dumb. How about looking at it this way: $250 for a decade of high bit-rate upgrades and album covers for the free music acquired on Napster. I know that probably covers a lot of Beatles, Metallica and AC/DC fans that could not buy legitimate digital versions of albums until the past couple of years.
iTunes Match is a good thing for consumers. It's forward thinking and should be rewarded. I plan to give gift cards to some people this year with the suggest they buy a years worth of iTunes Match.