I have been playing the latest IOS beta from 03/15 and am finding the larger and re-arranged buttons, bigger menu text, and other changes make for a much smoother playing experience on the touch screen.
I do have one issue that I keep coming across in game with Carapace, http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=184777 (and I would guess other cards that also allow you to sacrifice them).
In order to sacrifice them all you have to do is click on the card, on the smaller phone screen I find a lot of the time I am accidentally sacrificing when I really only wanted to select the card it was enchanting to view or declare as an attacker. Would it be possible to add a pop up menu that would come up with 2 options on these (sacrifice + cancel) instead of just sacrificing them right away?