In working with both the 2.x and 3.x versions a couple things weren't emphasized enough.
1. The need to use indexes greatly increases the speed at which the map is drawn and there is very little reference to it in the documentation and probably should be mentioned in the "Getting Started Guide" and/or the sample code.
2. If you use the new Map Suite Explorer (the one provided with 3.x) to index your .shp files they will no longer work with 2.x applications. Of course that means you cannot have a common data source for both 2.x and 3.x applications.
3. Not only are the Zoomlevels expanded in the 3.x version but also (and this cost me an entire day of work before figuring it out) is that they are reversed, In 2.x ZoomLevel01 was maximum zoom and 3.x it is ZoomLevel20.