Not too great
Let me first say I'm actually blind myself.
Small point here, noone uses moon. Next to noone. Braille maybe, but not universal... but moon is pretty rare. It just isn't space efficient enough.
As to touch screens, look up the Meistro and Trekker devices at www.humanware.com. That/s an interesting set up where tyey use an overlay over the screen. There is also a package called Mobilespeak Pocket for Pocket PC PDAs (windows mobile), cna't eremeber the address right now but they have an option where you place your pointer on the screen and it announces the keys on a virtual keyboard as you move around. It doesn't use the standard one, it uses the whole screen as an audio virtual keyboard. These things can be worked around.
Most people who use speaking phones use the various versions of Mobile Speak, or Talks at www.nuance.com/talks. There are other phones that have integrated speech, but they're aimed at the older market and are very primitive. I'm perfectly happy with my Nokia E65 and Talks combination, which cost me about £150 for the Talks software from a UK distributor on top of the phone. I dread to think how much the talking set up for the iPhone would cost since specially designed hardware of any kind tends to bump up the price, a prime example being the visually impaired designed Pac Mate running Windows Mobile (www.freedomscientific.com) fpr the princely sum of $2,450, or from a UK reseller (they all have the same prices so you can't shop around) they charge £1650.