I love maps. I've had printed atlases for years, I have globes all over the house, and I had some of the early mapping applications for the Mac like DeLorme Street Atlas. Sadly, DeLorme abandoned the Mac years ago.
Suffice it to say that any new mapping application will get my attention right away. Let me direct your attention to UpNext HD Maps. It's a free app for the iPad that gives you searchable, zoomable maps with 50 of the cities rendered in 3D, and 23 with extremely enhanced details.
You can click on a building and see what businesses are inside. You can search for recreation, dining, shopping and more. The app is connected to Yelp so you can often find reviews of places that might interest you. There is also a deal finder which will show you any discounts at nearby locations.
The app requires an Internet connection, but can pre-cache recent places you've been when you're offline. In terms of performance the app was pretty peppy on a Wi-Fi connection, but frankly it would be very slow on most 3G connections. The data needed to render buildings realistically in 3D is not small.
You can find maps of everywhere in the United States, but you will only get the detailed 3D renderings in Atlanta, Austin, Boston, Chicago, Cincinnati, Cleveland, Dallas, Denver, Detroit, Fort Lauderdale, Honolulu, Kansas City, Las Vegas, Los Angeles, Miami, Minneapolis, New York, Philadelphia, San Francisco, Seattle, St. Paul, and Washington DC.
I did have a few crashes when using the app, and I noticed that once you venture outside the center city area, you quickly lose the 3D display. There are big gaps in information, so don't expect detailed info everywhere you click. Even so, this is a worthwhile app to play around with, and the price is exactly right. I'm hopeful that the app will get more stable, add more information, and include more cities.
The app works with any iPad and requires IOS 4.0 or later. It's a 16 MB download.
I've grabbed some screen shots which you can browse below.