Honestly if you have a whole host of apps/tools to already do everything you need (or really, if you're good enough with INPA/ISTA-P/WinKFP etc) then you don't need it. The appeal of it is it's made by the BimmerGeeks guy, doesn't have any features locked behind a certain adapter, doesn't require a subscription and most importantly it's basically the "BMW Standard Tools" in Android App format, with some of the more complex things still being added in at the moment.
Imo that person's review is flawed due to a lack of research:
A: Nothing is locked behind/paywalled by the proprietary BG adapters like Carly and other apps do, so he didn't need to purchase that in the first place.
B: Not only do you have to click on what thing you want to do before being taken to the store for the first time, but it tells you exactly what module you need when selected (i.e. he couldn't have gotten to the license purchase screen without first finding the "calibrate injectors" option, in which case a popup would've came up saying "We're sorry, but you need to purchase the
diagnostic module first in order to do that) and there's descriptions under each module's license that describe what they're for. The diagnostic one very clearly has "program fuel injectors" in the description (along with register and program battery, adjust idle, etc), and the coding module makes it pretty obvious it's for manipulating software options and functions like comfort access, customizing lights etc rather than performing maintenance work.
C: As far as I can understand, the app literally just downloads the necessary INPA daten files for whatever car it's connected to while told to download the data files, so I wouldn't be surprised if like
@Rob09msport suggested with it being user error. The guy probably has two different cars, was in a hurry so didn't read anything and only downloaded the data for the first car that he plugged in to, then tried to program his second car with the first cars' files. Which would be no different than if you were to open INPA, select "3 Series, E90, MSD80" while trying to reset adaptations on your F82 M4 lol.