I'm a bit of both - was self taught up to a point, then I took some in person lessons. They were definitely worth it - it put names to and reasons behind some of the things I was doing, helped me weed out some bad habits and opened my mind a bit to new things. I'm still a luddite in many respects (can only read music at a rate of a note every few seconds, don't know much theory), but I probably wouldn't have started writing songs without receiving a few pointers from someone in the know.
I didn't continue with the lessons, so I guess I'm back to being self taught again, but the few months I did them really helped kick things along.