I use BuySellAds, from a publishers point of view its great, all automatic no need to constantly email advertisers or worry about payment. From a sellers point of view (I haven't used it) its just as simple, although I have had one problem of a payment not going through, but it seems to be releated to that one person, others have worked. I like BSA, its perfect for bloggers. They do take 25% out but for the hassle that they have removed it is worth it. Big sites like PSDtuts also use it so it must be ok. They are turning over $1.5k and advert.
The whole process of selling and managing your ad spots is pretty easy and straight forward. Also, buying is pretty easy and fast too. For the time being, I'm not quite sure on how well it performs for small to medium blogs/websites. Some successfully sell ads, some don't. Obviously, statistics have a lot to do with the whole buying/selling process and decision, but some ads have good prices, still they don't sell. I guess it take a bit more time so that more buyers join the network since the service is pretty new. It's worth giving it a shot, and their website looks good too. Could use some improvement on the speed of the stats update tool.
I'm using it on my site (iconzworld.com). S far it has been pretty painless and strait forward. Not to mention the support is great. They are very friendly people who want nothing more than to help you out and see you succeed. They even pushed me (in a good way) to raise my rates and connect me with people who now advertise with me. It's a pretty simple concept. The more money that their publishers make, the more money they make! -Mike
I have signed up for about a month, and have had no interest in my blog. probably because it is new I guess.