The DTS CDs are, obviously, encoded with a lossy compression scheme (DTS). They can sound very good, but I have not found any that sound as good as either DVD-A or SACD (both of which are encoded with lossless compression schemes).
I have both the DTS CD and SACD of the Police Greatest Hits, where the SACD has the same surround track as the DTS CD, and the SACD is far superior in sound quality from my comparisons.
I actually prefer the mix on the dts CD. The DTS cd's are not as good as sacd or dvd-a but better quality then cd's in general and they usually have good 5.1 mixes. Don't hesitate to pick them up.