Most docs I am aware of don't use Wellbutrin alone. It's usually added to a SSRI to combat the sexual side effects, and to increase energy in general.
I was on Zoloft for 12 years (and did NOT realize how numb I was becoming emotionally) and mixing Wellbutrin with it did absolutely nothing to fix the problems they were shooting to fix.
However, last year I changed to Effexor after I decided I didn't want to feel dead inside anymore. They've added wellbutrin to that now, and it DOES work.
There isn't a single solution for everybody - all body chemistry reacts differently to these drugs, and what works for somebody else may not work for you in the same way.
I hate the idea that we're guinea pigs for the psychatric field, but it's really true.