A friend of mine who is also a live engineer used one for a show once, he said it sounded good and was good to use. We both work at a venue with a digico sd9 so that's the level of gear we're used to, so it's fairly high praise from him.
I've hooked up my iPad to control the mixer in my Fireface UFX before, you don't get every parameter available but every mix comes up on the faders. I've mixed a show using the UFX before, sounded really good and you also get a great soundcard as part of the package. Costs a bit more though.
Personally for the studio I think a great interface with flexible routing is better than a desk, digital or analogue.