the cheap fares bit of the app is good, but also accessible very easily in the drop-down menu under "cheapest fares" - quite a nifty tool to find the bargain fares here and there; sometimes some glitches (most commonly, any really surprisingly cheap fare you see in the "month by month" bar does not tend to actually exist in the "day by day" menu behind that) but it's not bad for some browsing

the reward flights section of the app is also a lot better than the BA website if you are being flexible