been using Maps on a Lumia 820 for two weeks now, and while the touch interface is of course a huge step forward from my previous E52, there are several (I believe essential) features that are strangely and desperately missing:
The basic map view is fixed to "north up" and doesn't show any indicator of the direction the device is pointing to. The E52 had both a compass indicator and an option to rotate the map according to the device's orientation. I find map orientation essential in "pedestrian mode", especially when you're in an unknown place. While we're at map indicators: when zooming, either with the pinch and zoom gestures or with the optional +/- buttons, the map does not show a scale or ruler which the E52 also did.
Both offline maps and microSD card support are unique characteristics of Nokia Maps and the Lumia 820. However, storing downloaded maps (probably the biggest data chunks on your phone) on the microSD card is not supported. You really have to the store your offline maps the phone's internal memory?
When you open your list of placemarks (or favourites), that list is sorted alphabetically. With more than a few placemarks (I have well over 500, collected over many years) that's almost useless, because you see named locations scattered all over the world when you're really looking for the name of that restaurant you visited somewhere nearby some time ago. On the E52 the favorites list was of course sorted by the distance from the currently displayed map area (or the current location), which is so much more useful.
Would be glad to see these in a future update.
As essentially Nokia Maps & Drive had to be started from scratch working within contraints of Windows Phone OS it can be hoped there will be further convergence with Symbian experience in future updates, although open access to map data may unfortunately be a step too far for Microsoft.