This program is an AppleScript that can encrypt files or folders. The app uses the encryption engine on your Mac to encrypt files and it doesn't really have a graphical user interface. This means that there aren't any options that you can change, except the password. So, basically, when you drag-and-drop a file or folder onto "Encrypt This 1.1.app", the script will create a new DMG image encrypted using AES 128 encryption. It will ask you for a password that you should enter twice for verification. The window where you enter the password has a password strength meter that can visually help to determine if you are using a safe password or not. The image file created by the program will be placed in the same directory as the file that was encrypted. So, you can keep this application on your Dock for easy access.
I tested this program by encrypting two different files and a folder in different attempts. I didn't experience any problems and the encrypted images worked as I expected. I couldn't access them without the password. The encryption speed wasn't really great and that is perhaps the only bad thing I can say about this app. I know it depends on OS X for the encryption process, but still, I have seen faster tools out there.
Encrypt This worked just fine on OS X Lion and Snow Leopard. This application hasn't been updated for some time, so I would rule out any new features or support for it in the future.