If you look back you'll likely find a post by me incredibly sceptical of CE when it first started, and my work phone wasn't compatible. I have however taken it on board over a long period of time and now find it incredibly informative, I use it as a tool to figure out who may or may not be genuine and reassurance that it's not just me being rude or moody.
Doesn't mean I won't accept bookings, and some reports are just agreeing with previous reports on basis of having read the report after the call but not actually experiencing any problem (I think some actually say they missed the call).
The main benefit over NUM is ability to see the report without having to dig into a website, just click and the information is there. That said I am going to get back into the routine of searching here and NUM.