Gridiculous is a great theme and has powerful features also in the free version. It's well coded, so you can modify features also acting in the code.
I do not give it 5 stars (that would be the correct evaluation because it's really great) because the theme until now has a little problem on some mobile Android versions. The central menu, that smoothly scrolls on iOS devices, does not scroll on some Android version, making impossible to navigate a website in mobile version on Android.
This information is valid until april 9, 2013. I hope that the great C. Bavota will fix the bug, transforming this theme in THE BEST THEME EVER to build simple, clear, powerful and ultra-responsive websites.