I really like wearing a shoulder holster, especially wehn I am driving for many hoursr at time (as I do far too often....).
I have had many different ones, and I can some up the golden rule very quickly:
Nylon = bad
Leather = good
The two companies that I like the most are DeSantis and Galco. I really like the DeSantis rigs with the WIDE front straps, I thought they would be harder to conceal at first, but they are not, and I find them noticably more comfortable than even other good leather rigs. Make sure that you USE the offside mag pouch(es) to even out the wieght load.