To get started, download the developer tools from here: http://bit.ly/bygDMU
If you have been working on a previous build, make sure you read the Windows Phone 7 (WP7) Migration Guide here http://bit.ly/9Myp7I
Pluses: The emulator is much faster and more stable than the April CTP and there are various api improvements and consolidation which will simplify development.
Minuses: There are still no Pivot or Panorama controls. Hubs, Photos, Contacts etc. are still locked down and not in the emulator by default. Also, I notice DropShadow and Blur TextBlock effects have been removed from v1.
Push Notifications - If anyone can get this working using the guidance here http://msdn.microsoft.com/en-us/library/ff402556(v=VS.92).aspx please do let me know, we have been unable to get a ChannelUri back when creating the HttpNotificationChannel?
Overall I would consider this build to be a pre beta in terms of feature completeness so proceed with caution. I doubt we’ll see the same level of churn as we’ve seen between April CTP and this first public beta, but there will be some necessary improvements and enhancements required, particularly around the missing features.