The best thing about this product is its flexibility in terms of scalability as well as ease with which it can be integrated into existing systems without much hassle! It's also relatively cheap considering all those features you get for free when using such platforms like MQTT etc. I haven't found anything really bad so far but yes there are some minor issues here nd there - mostly related to documentation (which could have been better). We use these modules primarily just for integration purposes where we need them most i.e., monitoring our equipment remotely via sensors/actuator devices installed locally; sending alerts from remote locations through SMS gateway & emailing notifications upon receiving an alert by one user device.