I have iTunes Match and the Music app on my iPhone is almost un-usable. Two major bugs are causing this:
1. Sometimes, a song will fail to play if it's not downloaded. I'll have it on shuffle-all and a song will come up and the app will pause for a minute (as if it's building the cache, which is fine), but then the song will fail to play and the next track will begin. If I go back to that song, it will immediately skip it. The only way to play the song, is to download it manually (with the little cloud icon) and it will play fine. HUGE pain in the butt when I'm driving.
2. More often than the first bug, a song will begin to play and when it get's to the 1-minute mark, it will skip to the next track for five seconds and then come back. When it comes back to the original track the counter will start ticking, but no music will play. The only way to get it to play again is to seek to before the 1 minute mark and hope it doesn't happen again (about 30% chance of getting through it). If it doesn't happen at the 1 minute mark it will sometimes happen at the 2 or 3 minute mark (+/- 5 seconds).