I have an evaluation copy but have yet to evaluate it. I was however sent in their direction by someone who uses it and is quite happy with it. I can forward your email to him if you'd like. Send a request to firstname.lastname@example.org and i'll forward it off.
We've purchased 15 licenses earlier this year, attended a structured training class and are using the tool right now. In terms of ease of use and short learning curve, it's not bad. We had a pressing need for mainframe IBM emulator testing that no other product could handle without serious programming customization. Certify is working wonders for our testers.
Great to see so much interest around the Keyword approach. If you want to "check out" an implementation of the "Key Word" approach look at SDT's Unified TestPro at [www.sdtcorp.com]. Regardless of the product chosen I [Build, Buy, whatever]highly recommend you continue to explorer this approach - it really works.