iTunes Match premise: Once a pirate, not always a pirate. Pirates are willing to pay $25 / yr for legit 256 kbps AAC tracks of stuff they already have? And you must keep paying $25/yr in perpetuity for access to these tracks?
I really don't like the part about legalizing my collection. The music I ripped and encoded myself from hundreds of CDs that I bought retail are just as legal as tracks from iTunes.
iTunes Match sounds like a way for the labels to get finally get income from the music pirates who torrent stuff off of Pirate Bay. A share of the $25/year is better than the $0/year they're currently seeing.
So instead of buying music, you can now "pirate" it, then allow iTunes Match to "legitimize it" for you.
Bingo, free "legitimate" music (I assume with artwork/etc included).