David McKenzie provides useful advice not only on whether or not to do a post-doc but also best practices if you do decide to do one.
My thoughts: Post-docs vary a lot! Some are really just high-skilled RA positions--which is not necessarily bad if you're learning a lot. Others just give you a lot of free time to pursue your own work--which is not necessarily great if you don't have a clear direction for future projects. My point: There is no clear answer to the question of whether it is good or bad to do a post-doc. It really depends on the particular post-doc position you are considering and the non-post-doc position you are giving up or postponing.
Good luck, JMCs!