My experience is 50/50, but it is enough to drive me away from the website.

The first international ticket bought on the website is fine. I bought it there just because it is several dollars cheaper than other websites.

The second ticket made me frustrated. I paid and the transaction seemed successful. When I checked the flight a day later on UA, I was shocked that there was no reservation at all. After some useless communication with the agency, I called the bank to dispute the amount two days later. Luckily my flight was months away and there was no change in ticket price, so I booked it again on Orbitz.

You may want to read another thread in 2010 as well.