Delivery was faultless and the design & construction seem good. (Longevity and reliability will have to wait). Connection via my Mac or iPad were straightforward, except that, like others, I initially had problems with synching via the iPad. This now seems to be resolved, and works fine so long as you make sure the Nike app is up and running on the iPad. The ability to review your history seems non-existent via the iPad, but great using a Mac (or PC).
The basic principle seems great : that it encourages you to monitor your activity levels day by day. If one day is light, you are prompted to compensate.
My main gripe relates to the things the Band supposedly measures. The band seriously underestimates calories consumed. Presumably because of how it measures (using accelerometers on your wrist) it fails to take account of many activities. The most obvious example would be cycling which is more or less ignored. It picks up some activity from rowing, but not as much as I believe it should.
Despite the partial recording of activity, its ability to encourage you to achieve goals is its key benefit.