Yeah it's a great tool for songwriting and it's usually my next step after the initial idea when writing a song. Whenever I hear a song I really like the harmony of I usually check the theorytab database, too, to see if anybody's deconstructed it. You can technically make full songs on Hookpad if you buy a subscription (or pay the one-time fee) since it has drums and other instruments, but I find that better to do in a DAW or with a band and just use Hookpad to lay down the initial structure.