Last time I purchased some from aquabid and Hung was my transhipper. I didn't have any major problems that I recall. Sometimes it was hard getting a hold of him/her by email and the communication could have been better, but it could have been a language barrier thing.
I think the idea of a transshipper is that it keeps honest people honest, and gives you the confidence of buying overseas, particularly if you're a very serious breeder of a particular bloodline, or expect to pay for quality and get it. I can see it's role in keeping the supplier credible as well, and gives the buyer someone local that he can go to if something goes sideways, like the wrong product shipped.