Android Simulation Changes:

Robolectric's handling of styles and themes is now much more faithful to Android's actual behavior. Missing styles (often from AppCompat) are now more likely to cause failures, so you'll generally want to set a theme, either through your manifest or programmatically.
Missing resources and attributes which silently failed or defaulted to platform attributes with the same name will now raise errors.
Robolectric's PackageManager is more fully implemented; e.g. you can now setPackagesForUid().

API Changes:

ContentProviders should be created using Robolectric.buildContentProvider(), which simulates how the framework creates them (and calls onCreate() automatically).
RoboMenuItems should be constructed with a context.
RobolectricTestRunner has been changed to make it easier to customize manifest loading, while retaining caching. If you have a custom test runner, you should override getManifestFactory() instead of getAppManifest().
You can enable style resolution debug output by turning on logging (by setting the robolectric.logging.enabled system property to "true").