|The general view looks a lot like Gmail minus the ads.|
Kite is a BSD-licensed open source Gmail clone that you can host on your own web server. It has a more minimalist interface than Gmail, and is currently fairly limited in functionality (and is an alpha release), but more features will be added soon. It gives you more control over your email by letting you self-host. Given what we now know about the NSA, hosting your own email server may be an essential tool in the privacy wars.
Will it be easy to install?
According to the developer Karim Hamidou, Kite uses puppet for deployments. This means that deploying a new mail server, including a postfix config with sensible defaults, can be done in minutes with minimal tech savvy.
The code and the issues are hosted on Github.