The best thing about this service is that it provides an extensive library of ready-to-use widgets. I've never had any problems customizing my Dashboard using its libraries. As for pricing - it depends on how many users are going to use the widget/dashboard. If there are only few people interested then you can easily get away with free version offered by the service. We have started integrating our internal tool with Cumul.io API and we were able to create very useful Dashboards without writing code at all.
ο»Ώ