I have installed it. It is actually pretty handy. Seems to give a really DETAILED account of your system, the components of your system, what software starts up with the OS, even has benchmarking modules in the "registered" version (still free).
I actually prefer it to SiSoft Sandra as it is easier for me to find information I actually want to see.
Certainly seems harmless enough ... only runs when you run it so it is not consuming system resources that I can see. Has never crashed or harmed my system in any way.
Right now Fresh Diagnose it is the only Fresh Devices module I am running but I'm curious about the others too if anyone is running them.