Log into your account and you'll see a list of restaurants based on your GPS location. You can also find deals and news, as you would on the Sherpas blog.
Ordering is a breeze. It runs pretty much as the site does. It's easy to select toppings and individual options for your dishes, and previously saved addresses are already available for you to choose from. The only thing I didn't see was an order history of previous purchases made on the website.
Sherpas says that they have a new and more accurate way of calculating delivery fees, so you might see some changes there. The only complaint I heard was from the delivery guy, but he says it was his first day using it, so he's not familiar with it yet.
All-in-all it's a very well designed app. You can grab it here on the Apple App Store. Android users: as usual, you'll have to wait your turn. No word on when that'll be yet. (Leave your angry Android-user comments below.)