I've only written fan fiction and I think it has been great fun. At the moment I am not feeling in a 'writing mode' but when I was inspired I alternately enjoyed the process and equally hated it when someone criticised something I'd written. I was not used to having my work questioned (and I mean my day job, not writing fanfic) so it was quite a shock and it taught me a lot...mostly that I wasn't perfect. LOL I already had a very good grounding in grammar, spelling and punctuation, but writing fanfic really had me looking up stuff just to make sure what I'd remembered from school was correct. I hope one day I will again be inspired to write, but it has been a couple of years so maybe by brief foray into it is all there will ever be.