Does anyone have experience with using 3rd party APIs for Zoho CRM development?

I'm building an external application that needs to connect to my clients' multiple resources, including Zoho. The unified approach is attractive, but I'm concerned about performance and support. One of the platforms I'm considering is Kloudless. They have a Unified CRM API product that seems to meet my needs.

Any feedback from those with experience using these unified APIs would be much appreciated!