Link ECU is super popular in the UK, probably half the ECU install's I do into Supra's use the SupraLink G4X these days.
I used to run one on my own Supra for about 4 years when I used to daily it. Overall I have no major complaints with the platform, it covers all the features I would need for most road going or club level race cars and can deliver it reliabily and smoothly. I must have around 100+ customers out there on Link and have been tuning Link for 8 years or so now, never had any issues with hardware reliability.
The logging on the ECU is really nice, probably one of my favourites to use. I wont compared every feature with every other ECU as that will take hours of writing, but in my opinion everything that is offered on the Link can compete with and sometime excel beyond their competition, so unless you have something really crazy that needs doing then Link will cover you. Like any standalone ECU, its only ever going to be as good as the guy calibrating it, so just make sure your tuner has good experience on the platform.