I used one about three years ago. Solid little PLC, for the most part. I used it because it has a 5V input card, which I needed for interfacing with another piece of equipment. Still going strong, as far as I know.
Serial COMs to a A.D. GS2 VFD sucked. I never did get it working; I had to resort to using digital inputs on the drive to do what I needed. The serial COMs may have gotten better since then - I haven't checked. It didn't help that A.D. has no programming example code for serial COMs with the CLICK, and their documentation regarding it is spotty as well.
It seems to be the trend with A.D.'s newer controller offerings - get them out as quickly as possible, documentation and example programming be dammed... but I digress.
If you need a low cost PLC to do simple combinational logic, with a minimum of COM's, the CLICK is a good choice.
-rpoet