Fellow Mclaren Owners, I write from the Philippines, where for years we have had no dealer support (dealer is only about to open now and we are not sure if non-dealer cars will even be serviced and if ever they do, it might be for a big fee) hence several of us Mclaren owners shared to buy the software together with the shop where we bring our cars to for repair. Essentially 5 of us shared to buy the software.
It has been a great tool for the short time we have had it. The software is easy to use and can do a lot of things... it has programmed a new key to my 12C and assist in replacing the accumulators on my 720S by showing live data on the pressures of the hydraulic suspension system. The common stuff like finding out what's wrong with the car is a breeze with the software.
Lastly, Younis is correct here, in that they offer full support in guiding you how to repair your car and what strategies can be used. The whatsapp group they formed is helpful too as you can get real time advice for your Mclaren needs. There is good service advice provided by technicians that is an extra service when purchasing the software.
Still, I understand that it might be cheaper to just bring it to the dealer. But for people that live far from the dealer or could form a group to share the cost, I think it's a pretty good investment. I surely could not have bought it just for myself and one car. But since I found 5 other close friends who all live in the same area and can go to one specialist, sharing the cost came out relatively cheap and easy to bear.