Does it claim to be better? The main advantage I can see is simplicity, even non-technical users should be able to figure it out.

The encrypted result of this tool contains all the code necessary to decrypt itself (in a web browser).

I'm not too familiar with GnuPG, so I don't know if that's different.

You can download this safely from windows. GnuPG doesn't have a valid ssl certificate (https://www.gnupg.org).