With this handy app you can scan regular barcodes on products and look up pricing and reviews. If you scan a book's barcode you can search inside the book for a word and find where it occurs (if the book is on books.google.com).
Or you can scan QR codes which can store anything from contact info, URLs, SMS or plaintext messages, and more. If you see a QR code on this site to download an app that you want, you can just scan your monitor and it'll take you to the place to download the app.
Usage of Barcode Scanner is pretty straightforward and easy to figure out. The only downside to it could be the fact that it does not retain a history of previous scans. Personally I'm not sure if that's a drawback or not, since I'm not sure I'd want it to keep a history.
So, should you download barcode scanner? The answer to that question lies in this QR code: