I installed the new build 9926. My fan is now definitely running as I can hear the "jet fan" sound as others described earlier. The new start menu and icons are more visually bigger and actually eye appealing. I'm going to run through other areas but here's the list of features from the Insider Hub...
This latest build includes the following new features and enhancements:
•Cortana on the desktop: Cortana is your new digital assistant. She can help you search your PC and the web, carry out tasks (like setting reminders), and provide personalized suggestions. You can access Cortana from the taskbar or talk to her by selecting the microphone icon—or go hands-free and just say “Hey Cortana” (turn on this feature in Cortana settings). To customize Cortana suggestions, open Cortana’s Notebook and add interests. Cortana can learn your preferences and provide smarter recommendations over time. Note: Cortana is currently available for U.S. English only. However, search will work in all languages.
•New Start menu: Expand to a full-screen experience and customize the color of your Start screen.
•New Settings app: We’ve made Settings icon-based and reorganized the categories to be more familiar. You can also use Search within the app to find the setting you want, as well as Control panel pages.
•Easier connection to wireless audio and video: We’ve made it much easier for you to find and connect to wireless audio and video devices that support technologies like Bluetooth and Miracast. To connect, select the Connect button in the new Action center, or use the Windows+P keyboard shortcut from anywhere on your PC. When connecting to wired and wireless screens, choose to Duplicate or Extend the desktop to control a device's projection style.
•New Photos and Maps apps: The Photos app will show your photos stored locally on your PC and OneDrive, and give you a bevy of editing options. Note: Some features, like the ability to create albums, are not yet enabled.
•Windows Store Beta: The NEW Windows Store Beta is a *gray* tile in the Start menu or on the taskbar and the current Windows Store remains available in the Build as a *green* tile. Both the app selection and markets where the Store Beta is available is limited for now, and only basic functionality is available in this release. You can browse, search, and download apps. International credit card, gift cards and PayPal can all be used to pay for apps and games. In-app purchases aren't available for apps downloaded through the Store Beta, though apps you already own with in-app purchase capabilities can be used. However, the ability to purchase additional in-app content is currently disabled. You can purchase apps on a device running Windows 8.1 and use those apps in this build of Windows 10, but not vice versa.
•New Xbox app: For details on the functionality the Xbox app has in this build, click here.