Blades' post above nicely lists all that is good about drum maps. Myself, I use Addictive Drums 2 and make my own maps using the standard AD2 map as a starting point. Generally what I do is use the mouse to pull all the things I want to use in a particular song down to the bottom of the map. Typically, the kick at the very bottom, snare and hat above that, then toms 1 thru 4 (both rim-shot and open versions), then cymbals & other percussion. I find that having the real name of the instrument at the left is extremely helpful. There's two disadvantages of using drum amps, though:
You can't edit 'drum map' midi and other midi in the same window. (I can't imagine how it would work anyway).
Once you assign a midi track to a drum map you can't make a single drum "instrument track" linked with the drum audio track. It was always that way in SONAR and still is in Cakewalk. I'd love to see that fixed some day but I've learned to live with it and it's not exactly a big problem. Having the drum map is still worth it to me. (Admission, I am a drummer).
Edit: I stand correct on my point 2 above. I just tried to make an instrument track with a 'drum mapped' midi track and it actually worked. First time ever for me. I guess I should have tried it one more time before I posted. But it never used to work. Honest.