I've bought, and sold, many things via Craigslist. I funded a cross-country move by selling the things I couldn't fit into my truck and u-haul trailer using Craigslist.
Having said that, I dislike the meeting-up aspect of Craigslist. For all of the money I've "made" by selling my stuff through them, there have been countless times where the person on the other end of the phone never shows up and leaves me there waiting.
Overall, it's been a positive experience. I'll continue using them for the foreseeable future.