The few DVD audio discs that I have listened to were amazing. The problem is that many of the cheaper DVD players don't even play DVD-audio, and many of the media stores don't have the music that I like on DVD-audio. DVD-audio can actually cover many different formats: 2 channel @ 192 kHz to full 5.1 surround @ 96 kHz. A year ago when I was looking at DVD players, I found I could get a nice cheap $45 DVD player at Walmart but the cheapest DVD player at the time that played DVD-audio was $150. DVD-Audio cannot be delivered via unencrypted digital audio link at sample rates higher than 48 kHz (i.e., ordinary DVD-Video quality) due to concerns about digital copying. So in the beginning you needed a bunch of analog ports to listen to it, although fortunately they later included DVD-audio sound to pass through HDMI 1.1.
So because of all of the crippling mechanisms built into DVD-audio when it first came on, only the true audiophiles were using it. Once it was finally allowed into the HDMI 1.1 and beyond, at that point hardly anybody was interested in it anyways. The early adopters had to either hack their hardware equipment or feed it through the pre-amp using 6 different analog cables which is a major PITA. Because so few people were using it (thanks to all of the crippling mechanisms put into place), early adoption was slow, and interest in the format has dropped. Because of the general lack of interest in the technology, the recording industries have hardly bothered to release many DVD audio discs. On top of that, if something malfunctions with CPPM, it cripples that player from playing any DVD-audio discs in the future (disables that feature).
It's pretty sad really. The few DVD-audio tracks I have listened to (via dvdcpxm) have been truly superb; at 192 Khz in stereo you can hear things in a song you might not have heard otherwise. The DRM mechanisms are so draconian that even home musicians were put off from making DVD-audio for a while, although there are a lot more tools now in 2008 than the past couple years which finally are beginning to allow it. There are about 200 DVD-audio discs available on amazon.com right now, compared with 1,690,000 CD's. Last time I scanned through many of my favorite artists didn't have DVD-audio available at all.