Awesome job, Andrew. It's very cool what you've built.
A few nits:
- I didn't realize "Try It Now" was a link to play with the product without signing up. This might do better as a button.
- I think the great Jotleafs that people have created really show the potential of the product and provide the inspiration. It would be great to put that stuff at the forefront a bit like you've done with Your World of Text (the homepage is a canvas).