It's an interesting idea, the first thing I noticed was that the design doesn't look very modern or professional, it gives a bad first impression.

The outer glow on the logo is kinda tacky. I can tell you've invested a lot of time into this, so investing in a really talented designer/brander might be something to look into.

Your mac screenshot image covers up half of the learn more and sign up buttons. It's an easy fix, give this selector ( body.brochure.new_index #landing.box #screenshot a )position: relative and give em a z-index:1000 or something.

Also, you have a lot of serif fonts, maybe you should consider making your menu and header text sans serif?