Aside from the obvious note-jotting ability, Google Keep can also create check-lists and add picture reminders. For the typing averse, it takes voice notes which are transcribed to text. The app includes a search function to help find particular notes.
All of your notes are stored in Google Drive and synced across devices.
A widget can be placed to keep notes at the fore, and notes can be dragged around and colour coded. A lockscreen widget is also available (for Android 4.2+ devices) for quick note taking.
Google Keep is available on Google Play for devices running Android 4.0, Ice Cream Sandwich and above.
You can access, edit and create new notes on the web at http://drive.google.com/keep, and Google says that in coming weeks users will be able to do the same directly from Google Drive.