Once you've activated the trial, you can see it work immediately by opening the dialer and trying to place a phone call. Shake the phone to bring up a search menu, which lets you search contacts by pressing the numbers on the phone keypad.
This seems to work pretty well, although I'd like to be able to click the search box and get a keypad to type from, as using numbers to correspond with letters seems so 1999.
I do like the photos in the favorites menu, which is much easier to use when you need to dial someone quickly. The speed dial option is nice, once you have it set up, and there are plenty of tweaks to play with, but overall, I find it to be too much, and more trouble than it is worth. As a trial, it's nice, but I wouldn't pay the 7.99 they are asking.
I like apps that speed up my user experience, but with iSmart Dialer, I feel like I'm moving in the opposite direction, and complicating things that need not be difficult. If you would like to learn more, you can visit their website here.