Couldn't agree more. I've bought and sold loads of stuff on Ebay over the years, with only one or two problems. On the stuff I've sold I've got better prices than I would have by selling by other means. The things I have bought have saved me an absolute fortune over retail prices - and all delivered to my door.
You can get problems buying and selling items through any means (for example, who's never had a problem buying or selling a car through the small ads?) - but if you are careful and go in with your eyes open, there are some great deals to be had. For choice and range of products, it's unbeatable.