So as you may have noticed if you're an iPhone fanboy, a comany called Navigon released a fairly good looking GPS app ahead of TomTom. Wish you could check it out, even if only to see how the interface feels? You can, kinda. Use these instructions to get yourself a free iTunes account in Australia, then search in the app store for 'navigon', and you'll see (and download) they released a free 'lite' version of their app (itms link to .au store).
Of course, unless you're in Australia you won't be able to use it, and I have no idea if it'll even run or just bitch that you're on the wrong side of the world. However, in theory it'll give you a demo and you'll be able to get a feel for things to see if you want to drop the $69 (or $99 after Aug 15). Also as this is a lite version there isn't any GPS or "active route" support available anyway :)