Sorry Nick, missed this one.
Anyway, the rules are evaluated top down, as soon as one matches evaluation stops and the conditions are set to whatever that rule states (just drag them up or down to set the order).
The default rules can be expanded, especially if you have additional sensors - I have rules for sunny and very sunny based on solar radiation and things like 'Damp' based on the leaf wetness. Sometimes however it isn't possible to calculate the conditions and that's where the manual entry is useful - things like 'snow' or 'muggy'.
The big issue with it currently is you can't set up more complex expressions - this will be dealt with in a future release.
