While I want to get healthier, Rally wears on you to a point it becomes demotivating. At least two times a day you need to resynchronize you health tracking device with Rally. Its just like at any time it disassociates your step tracking. Additionally it does not track any other health stats like weight or heart rate that can easily be tracked yet its just a check, yea I did it.
As far as the coins, for the 15 or so items in the marketplace is a good starter but after 3 months, not one change to the marketplace, this should be constantly rotating to encourage you to keep going. But the biggest disappointment is the auctions. On average auctions costing 250,000 coins, that is like 10 years of tracking activity, might as well say you will never be able to buy anything in auction.
App just requires a relook at what its really suppose to do, encourage or discourage you becoming healthier. Currently long term it discourages you.