I've used Buyee a of couple times, mostly for Yahoo Auctions. The system works quickly in terms of bid-placing and also automatically sends you an email every time you are outbid -- I am immensely glad for this function. My only gripe thus far is that the shipping & handling fees are a little high compared to regular mail forwarding sites. I do understand that part of the cost is also the "service" involved in getting the whole process done though. Pure shipping costs also seem mildly hiked up -- they offer a direct to ship option now that is quite honestly incredibly exorbitant (you can however also opt to calculate shipping proper when the products reach their warehouse instead).
Despite that, I'd still use them again. I already know they are reliable, so the higher costs just seem like something additional to factor in my personal budgeting.
I haven't had to deal with their customer service yet, so I don't have anything to say about that. I hope things are fine in that regard.