I tried to use my phone (Samsung Galaxy S2) for the ireal program at first, and after about 2 gigs I gave up and then bought a Motorola Xoom android tablet. I found that the small screen was ok in the bedroom/practice but anything live was just too small, especially if was looking at other things (crowd/band members etc) and then went back to the screen, finding my position was hard. The tablet was awesome, as I could also get rid of my music stand and get a half mic stand with a holder and the bigger screen just killed it as well.

I have since sold the Motorola and upgraded to an Ipad 4. I'm not a OS or Android lover/hater as I use both, but I found the IOS version of irealb/pro smoother on the IOS version and (this may have changed) it seemed to get the updates and newer features first over the android version. The big plus for me was the other music apps that are available on IOS absolutely killed anything available on android - it's commonly agreed that music apps on the android system are harder to get right and do because of the openness of the android system (which is great BTW i have it on my Samsung S4). Garageband has been mentioned, but other apps you may want to look at that I use daily are Anytune Pro +, Audiobus, Jamup XT, Tabs HD.

These may be enough to sway you to get an ipad, or may not , however I would suggest a tablet would be a better choice over phone, at least for irealb!