Very cool styling - there are some messaging concerns as karolisd mentioned.
For instance, I was a bit confused as to why I was reading about other services / how you don't change my inbox labels and configuration instead of reading about what you provide. (The "Manage your inbox, don't change it" messaging)
Are you A/B testing your goals and content? Your email signup goals are fantastically straightforward which a ton of sites are lacking.
Full disclaimer: I am helping with a framework called Xander (http://www.xander.io) that does multivariate testing - let us know if we can help. There's also optimizely which is a YC startup and pretty cool for straight A/B tests.
Thanks for the feedback! We're not yet A/B testing the landing page yet (working up to a more public push where that will come into play). That's a very interesting point about discussing our competitors instead of ourselves.
Xander looks pretty cool. The Google Analytics tie in is crucial. I'll probably be testing it out in the coming weeks.