How useful it will be on a daily basis is questionable. Google Handwriting Input is a neat tool, and an impressive piece of technology. There's an option to send Google reports of your usage of the app, which will help its recognition software improve. It's not infallible, but if you're a neat writer, you'll probably never see it make a mistake.
You can write surprisingly messily and still have Google Handwriting Input correctly work out what you wrote. As well as recognizing handwriting, Google Handwriting Input can recognize drawings of emoji, and it's pretty impressive.
