Down now, but a solid service.
I've been using this since day 1 and while I experience odd things too (ie that track in the middle of the album that is uploaded while all the others are matched), this just doesn't seem like a big issue. A lot of what I add to my library is pre-release (I review music for a living) so most of what I add to my iTunes Match is uploaded. But what's the issue? I get the songs from the prompter, add them to my iTunes, it uploads and 10 minutes later it's available on all my other devices with id3 and other iTunes meta information sync'd. Great.
NOW the issue today (and yesterday) is that Match appears to be down due to the influx of all the new users. I've had 10 tracks (the new Halloween, Alaska album sent to me yesterday in hopes I'll write something about the band before their gig in Lawrence, KS in February) that are stuck in the "Matching Your Music..." step. Hopefully the servers will calm down soon and all will be well.