Like most keyers, I did have some initial issues trying to use it. I would just slide the knobs back and forth to try and reach the desired mix, with a few problems. After watching the tutorials on the PHYX website, it all became much simpler. There are still some shots that I'm having trouble removing that pesky halo from, but that could be my ignorance more than the plug-ins effectiveness. It most likely has to do with the way the footage was shot. You should never shoot footage out of focus if you plan to key it. The shots I am dealing with have a focus rack between foreground and background characters. That's a no-no when it comes to shooting for keying. I can say that the tutorials are very well done. Every company should offer detailed video tutorials with their products, because it helps you understand the interface well enough to want to make that particular effect one of your "Go To" effects. PHYX is right on with their model.
PHYX Keyer lands in the low end of the cost range for Keyer Programs, and is less than half the price of Primatte or Ultimatte. Given its ease of use, I would say that it is a great value for the money.
I have been editing this somewhat high profile piece for some time, and the mattes were not always lit properly. I had tried several different solutions including Keylight. For some of these shots, I was just unable to pull a good key, and thought I was going to have to resort to rotoscoping. Luckily, PHYX saved the shots relatively quickly, and allowed me to cut a quick trailer for the producer who was hounding me for weeks.