I've implemented some use-cases for t-mobile, they basically peddle our products as a whitelabel solution to municipalities. One of my biggest beef with nbIoT is that 90% of all the use-cases I designed would have been better of using LoRaWAN instead. The reason why nbIoT is chosen is obviously that it provides the operator recurring revenue via a data-SIM but apart from costs there are other massive drawbacks such as energy draw of an nbIoT enabled sensor when compared to LoRa.
nbIoT is justified if I know that the data volume of my "solution" might increase due to feature/scope creep (and replacing the battery/sensor isn't going to become an annoyance in 2-3 years at end of life).
For most use-case LoRaWAN makes more sense but doesn't have the same marketing budget that is available to T-mobile, Vodafone and Co.
