The only downside I have found with the Freelancer career (which I played in the Artist track) regards the Renaissance Sim Aspiration, which requires reaching at least Rank 3 in three separate careers.
Because Freelancer doesn't have promotion or ranks (although one can with good job performance raise how much a gig pays), it prevents advancing this Aspiration. I had to quit Freelancer, and pursue a couple of other careers long enough to meet the requirement.
That aside, I love the flexibility, open schedule, and choice of gigs to complete. It seems Painting 8 is the highest skill required by any gig. I haven't tried Writing or Programming, yet, but pay is pretty nice in the Artist track.