Overall the product is well designed, easy to understand and works well.
The technical documentation is thorough.
The pricing is reasonable. The initial free package is generous and allows to do much before paying the first dime.
Customer support is fantastic. I've been sending tons of questions to their technical expert, Sumitra, during our integration phase and she never failed to respond within a the hour (couple of hours max), or jump on a call to further assist.
Although apps can do much within the free package, some fairly basic features do require payment, such as being able to get the list of users who performed a specific action. Not having access to such features within the free package has made testing and reporting more difficult.