It's not what the cycle computer does or what the smart phone does that is the true attraction. That lies in the simple using of an electronic device and the fascination of translating experience into numbers. Think back to the days before we had all this stuff. Cycling was just as much fun. I suppose there is no harm in using these devices, but they are really unnecessary. I have a simple computer on my road bikes but nothing on my mountain bike. The only difference between riding one and the other is that on my road bike I know how fast I am going and how far I went. If I am cycling to a destination on my road bike, I know how far I have to go. I pretty much know the same things on my mountain but not with precision. As Marshall Mc Cluan pointed out with regards to T.V., "the medium is the message." But no harm done if you like this sort of thing.