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.