We use it for our entire organization, everything from HR to Payroll processing as well as customer service inbound phone calls with SMS reminders back out of band (OOB).
The interface is very intuitive- easy navigation between any page within their suite makes me feel like I'm using my computer again instead of an outdated application that requires memorization! They are constantly working hard at improving this product - they've added several new features since we started about 2 years ago including more robust analytics capabilities which has made us even happier than before! Their support team takes care of you every step along your way; nothing's too big or small when dealing w/them so far!! Try them if you're looking into integrating software such as Sage Intuit QuickBooks where there can be some integration issues! Our Salesforce CRM system cannot connect directly through ODBC but Rhein allows multiple file uploads per day via CSV files.