I used B5 consistently for one week. I took 2 1000mg time-release pills in the morning and 2 more at night. By the third day I had noticed minor stomach discomfort, and by the fifth day I was waking up to small pustules popping up all over the place. This breakout continued for the next couple of days, at which point I stopped taking B5 altogether. My skin returned to it's normal baseline within two days of stopping the B5 (light acne, but not at the severity brought about by the B5).
The B5 did not nothing for my oil production either within that week, although I recognize that my dosage and length of treatment was not comparable to what most people here are doing (although according to reviews for this product on Amazon, many people are successful with 4-6 grams of B5 per day). I wanted to start out slowly, and given the reaction my skin had to B5, I'm glad I did.
Lots of people report success with B5, so I think this might be worth exploring for many acne sufferers, but it only made my skin noticeably worse. I would recommend starting out with a reasonable dosage; I found Amazon reviews for B5 to be much more helpful than the typical extreme recommendations made on this site.
Best of luck to you.