Is it worth to learn haml & sass?

My current web site has over 800 Haml files and 150 Sass files, and let me tell you it has helped my development tremendously.

The biggest boon is in terms of rapid development: creating Haml/Sass files requires far less typing, so you can nail out your presentation logic with far fewer keystrokes than if you were doing an erb template.

I also find Haml files far easier to read, and less error prone.

YMMV, but I have reached the point that not using Haml feels like a chore.