What is it?
Google App Inventor is a new innovative way to create Android applications for users of any skill level. App Inventor throws code writing out the window and introduces a new visual design style of creation using drag and drop methods for interface building and "blocks" for application logic and behaviour. App Inventor uses a simple and intuitive web based graphical user interface that runs on the Java platform and will allow you to test your application via a connected phone running the Android operating system at any phase during the creation process. The simplicity of App Inventor is also great for educational purposes to teach logic flow and the basics of application development.
The Design Interface
The design interface is used for creating the layout and overall appearance of the application. On the left side of the interface is a column of user controls that consist of things like text boxes, labels, buttons and the like. There are also controls for adding media and sensor functionality. Located in the center of the design interface is the virtual phone screen where the controls are dragged and dropped. On the right hand side of the interface are the properties for the currently selected control. For example, if a button control was selected, you could add an image or adjust the color and size of the button. The interface is nicely laid out and very easy to use. I threw together the application shown in the picture to the left in a matter of minutes.
The Block Builder
The block builder is where all the application logic and behaviour is put together. Like the design interface, the block interface is simple and intuitive. Under the section "My Blocks", a list of the controls that were added in the design interface will be displayed. Clicking on a block will give a menu of logic blocks or events such as click events, do while loops, play sounds and the like. In my example shown in the picture, I took the click event of the button that I added in the design interface and connected it with a play sound event. Located near the top of the block building interface is a button labeled "Connect to Phone". Clicking this button will export the application to the connected Android phone for testing purposes. In my example, when the application is exported to the phone, tapping the image will result in a siren sound clip to play as defined in the logic of the block builder. This portion of App Inventor is extremely easy to use, but an understanding of programming logic will be required for more advanced applications.
From my experience with Google App Inventor, I feel it is a really strong base for opening up Android application development to an array of people with the desire to create applications. It can be useful for experienced developers to create applications quickly and efficiently, and can also be a great doorway into application development for those lacking the knowledge or experience. I expect App Inventor to expand on its capabilities as it matures. I give it a two thumbs up!