Has anyone ever used hotwire.com for airline tickets? Is it reliable?

It's reliable since the major airlines own it. It doesn't save you much in many cases, however!

The downside is that, like Priceline, you can't choose times. Prepare for a 5am departure!!!

I tried it once. The prices were great, but as a previous poster said, you can't pick the departure times. Since the availability obviously would be at the least popular times, I didn't think it was worth the gamble. (Another negative, though less important, is that you don't get an ff mile credit with the tickets.)
I ended up booking with the airline's website and actually got a pretty good price, though not as good as hotwire. But, at least, I got to fly when I want to.

Try www.qixo.com first which will show you hotwire's fare. Not always the cheapest. And for what it's worth I think 6am is the earliest fare they can book you , so you can sleep in. You will most likely get what ever flights are the most difficult to sell. Hello , 6am.

I think you'll find that Hotwire is only worth while if you have to fly on very short notice , and even then it may not be the cheapest choice. If you have time to plan you can almost always beat hotwire and KNOW when you'll be flying.