The app works by building a model of your body clock, so if you normally wake at 7 AM and go to bed at 10 PM, it'll start working out the best way to painlessly adjust your sleep cycle. When you schedule a trip to a new country, you can start making tweaks ahead of time. It does this by telling you to spend periods in darkness and light, since it's these stimuli that affect your ability to regulate your body's rhythms.
How this works in practice is that if you're preparing to fly from the UK to the US, you should spend three or four days beforehand with a 10,000-lux lamp pointing at your head overnight. When you then land at the other end of your journey, you need to plunge yourself into darkness just as the day begins. To this day, I can't work out if I'm meant to be sleeping or just sitting in rooms with a blindfold on my face. The university asks you submit your lighting schedule to the app so it can tweak settings accordingly for the following day.
There are two problems with this approach.
Firstly, the app isn't particularly well designed, and while I feel bad for kicking sand in the eyes of the graduate students who put this together, it's not that easy to use. You select "Schedule Travel" for instance, and set a regime, but if you mistakenly go back to the dashboard, you have to reselect and reschedule your travel if you want to go back to your pre-arranged program. Given that it resets the start date of your program at this point, the app was advising me to start training for a trip in October on August 14th. Rather than being able to simply bulk-select which hours you were in "light" and which you were in "darkness," you have to press each hour slot individually until the correct option comes around, which gets tremendously tiresome.
Then there's the fact that the sort of people who need to overcome jetlag quickly and efficiently are precisely the sort of people who can't follow the program because they have jobs. Those "dark" and "light" periods before my flight would have directly flown in the face of my working hours, and I doubt too many other people could legitimately not come into the office because they're "entraining." On my last trip to San Francisco, it was lunchtime, and I had to go from the hotel straight to the office. The app, on the other hand, advised me that I should sit in a darkened room for the remainder of the afternoon.
If you're on holiday -- or you have very understanding employers -- this app may offer some benefit to your future trips. If you have to work for a living, I'd suggest doing what I did: If you're able, just take your running clothes to the office and go for a nice long run when you clock out, drink plenty of water and eat dinner at local time. It's not perfect, but if you don't have infinite free time, struggling on through the headaches and lethargy is still your best solution.