Got the mixer in yesterday afternoon. It wasn't supposed to arrive until Wednesday, but sure enough, Gear4Music somehow managed to get it to me less than 36 hours after I bought it online.
Tried the Behringer X Air app on android, absolute crap. Tried MX Mix, marginally better. Tried Mixing Station, and now won't be going back to either of the other two apps.
Just been able to plug some guitars, a mic and my bass in so far, trying to hash out the input gain levels for our band by using the same gear as will be used by them. So far, a lot easier to use than people seemed to suggest.