The Sky+ application isn't what you could call revolutionary - we've been able to control Sky+ from a mobile since 2006 after all. In fact the Sky+ app isn't even adding functionality that wasn't already available on iPhone and iPod touch, though. An application called TV Plus has offered Sky+ control on Apple's device's has done that since last year.
However, the Sky+ application does have one factor in its favour: it's free. wTV Plus, conversely, will set you back £2.99. It doesn't take a genius to see which offers better value for money.
Functionally the Sky+ application works as you might expect. Programmes can be chosen from the seven day EPG, selected to view the description text and then scheduled for recording. Sky warns that recordings must be scheduled 1/2 an hour before the start of the programme to be recorded - suggesting there's a fairly significant delay between scheduling via the application and the command actually being passed on to the Sky+ box.
It's just a shame I don't have Sky, really.