IMO it is The Best. I use CDA for mastering, as it offers a conventient way to skip around the whole CD for eay quick comparison and tweaking of tracks.
CDA5 comes with a standard set of plugins . It also has access to all the other DX plugins that you may have installed, including the Izotope ones if you have SF9.
Your resultant CD may sound better, or may be totally ruined by what you do. That is nothing to do with CDA though ! CDA does also offer straightforward way to sequence, space, and level your tracks, as well as the 'mastering' functions.
I agree with all of the above comments. However, you should be aware that CDA does not support VST plug-ins. The Sony plug-ins are pretty good and Izotope (Ozone 3) still supports DirectX, but who knows how much longer that will last.
CDA is surely worth having, but has some limitations.