I have to agree with Hickster's comments (and many others here!)
My mum's only had her Cooper a few weeks (her first MINI) and already she is perfectly happy with the start/stop function and just lets it get on with stopping when it wants to!
As Hickster said, i now find myself sitting in traffic in my R50 ONE thinking 'i should turn the engine off, what a waste of fuel
' Good on MINI and BMW, for being one of the first to get this feature into production cars!