My employer was paying, so I wasn't really looking for a bargain. And I bought a refundable, endorsable ticket, which is certainly no bargain. I chose them because they have a good reputation, and by and large they lived up to it. I had to call them a couple of times to sort a few things out, and as long as I called during daylight hours (in China!) I got an English-speaking agent who provided good service.

The drawback is that after I changed the date of my flight, the itinerary wasn't updated on their web site. They assured me that the airline has my updated itinerary, but I can't get a formal-looking printout of my flights (just their very informal e-mail).

That's my experience - but I've only used them once.