For me, one huge disappointment of iTunes Match was the pseudo-streaming. You could play music that wasn’t on your device, but the file would still be downloaded in the background. Which, of course, is ridiculous.
In iOS 6, that’s changed, at least in the first beta. Now when you tap to play a song, it begins playing, and you still have the option to download it. With iOS 6, you can choose to just listen right now with an online connection, or download for offline listening. iTunes Match has become a streaming service in the beta.
Now all they need to do is make it reliable, which is the other part of iTunes Match that sucks.