I have used them and they seem fine to me. I was promoting OverStock and SierraTradingPost via their product datafeeds, which unfortunately I had to get from their sites and not linkshare as linkshare charges for the service for small affiliates.
I did pretty well with these via my product price comparison which I ended up shutting down. I even managed to get just over $100 for one of the sales with overstock. It's not really much though considering the sale was for just over $1,000.
About payment. Yes I did receive payment, but occasionally I would find that I would have about 5 checks from them in a week or 2 weeks period for small amounts instead of having just one larger check.
Don't know why they done that. lol