Differences of white balance are quite small for standard D65/D50 targets, but noticeable. It's getting much worse when we calibrate the desktop display to a custom wtpt to get a match with specific paper in specific condition - why not make custom white point choices with fine tuning tint sliders?
It's even worse when we want to use Print Emulation feature - for example I never use Fogra39 profile created with ProfileMaker, I prefer ECI ISO Coated v2 which is most popular in EU, and of course my own profiles created with i1Profiler, which have slightly different perceptual rendering. And if I would like to simulate the print from my Canon iPF8300, I'd be completely in a forrest!
If you're calibrating a desktop display, you can arrange the surround to reduce the influence of viewing conditions, in case of mobile devices it may be impossible, so the Ambient Compensation feature could be very useful in such cases. ColorTRUE is calibrating the mobile devices to a TRC gamma 2.2 - at least I suppose so, as the created profiles are hidden in a cloud and not ICC compliant, so you can't really be sure, nor make 3D gamut charts or use mobile device characterisation for soft proofing on desktop displays (which could be useful for mobile device application developers/designers). What you actually perceive on a mobile device in a darkness is visually more like - let's say - gamma 1.6-2.0, while in bright, outdoor condition it's more like gamma 2.6-3.0 calibrated display... But the Ambient Compensation function doesn't really work, it only changes the chrominance slightly and doesn't change the TRC at all.
I can imagine it might be useful to edit image colours while actually watching the scene, to get the exact impression, or make colour notes. It could be even more useful in case of architecture/product/fashion outdoor photo session. It could also be used to simulate the appearance of a print. Problem is that due to the above mentioned limitations it doesn't work as it could - at least from a perspective of picky "colour perfectionist" it's advertised for.