I haven't signed up for the paid version -- yet. Only used the free product, and have found it very impressive for what it offers. I can gather a pretty good set of KPIs from readily available sources. My team can each set up their own databoards, concentrating on what they need to know. It's nice on the eye as well.
The only issue I have, which I don't know whether it's addressed in the paid version, is being largely limited to data from "last 7 days" and "last 30 days" -- with the occasional 14D and MTD windows. No quarterly, six month, this year, last year data. What I'm referring to are the dropdowns in the individual KPIs. It does seem, however, that the "Goals" feature supports some version of historical data, but I haven't used it, so can't comment on that.
Seriously consider the paid version if you have custom data sources.
Having a lot of what I need to know in one place so I can daily track specific KPIs in an easy-to-use, all-in-one package app. I look forward to hooking up our custom data sources so I'll have *everything* I need.