First, let's talk about presentation. While exploring Southern Arizona, I found HERE Maps to be as outdated as my car's built-in system, which is also powered by NAVTEQ. To my eye Apple satellite views are cleaner and certainly more current. That may or may not be true in your area, but there are many App Store customers bemoaning out-of-date data.
The POI database also seems weak, and suggested several restaurants that are out of business. Apple has issues with that as well, but Nokia is trying to improve on Apple Maps. Some of the on-screen icons are a bit arcane. It was hard to figure out how to start navigation once a destination was selected. There are no onboard instructions. There are no 3D views, and you don't get an on-the-road perspective as you drive, just an overhead view. There are turn-by-turn directions, but you must download voice files after you install the app. You can have your choice of voices, as long as it's the one British voice offered. Apple Maps also doesn't offer a choice of voices. One gotcha- voice directions don't work when you are driving. Only when you are walking. What were they thinking?
Maps are similar in detail to Apple Maps, but they are not vector based, so they redraw often while Apple's maps are crisp when displayed.
In my tests, HERE Maps don't have the festival of errors Apple had on launch. No street views that look like Salvador Dali nightmares. The app is certainly usable, and if the mapping is better in your area than Apple Maps you are ahead of the game. I just don't see this app as a big leap over what Apple has provided. It's only version 1.0 for iOS, but it has the feel of a web app rather than a polished piece of software.
My advice is download it and try it. If you like it better than Apple's Maps, go for it. The fact that it is in the App Store at all suggests that Google will get there with an app that is better than the Apple or Nokia offerings, but of course the non-Apple apps won't have the iOS and Siri integration that is so nice with Apple Maps.
The HERE Maps app is a 3.7 MB download and requires iOS 4.3 or later. It is optimized for iPhone 5. Voice files are an additional 1.5 MB download.
You may have a very positive experience with HERE Maps, so share your comments with us. There are some screen shots in the gallery, and a comparison to Apple Maps satellite views of the same area.