Nothing not to love about GMail. Been using the service since launch in 2004, never looked back. Once you get past the "why can't I have folders?!?" mentality and learn how to use labels, you realize just how much better a system it can be. The web client is also better, IMO, than any of the others out there.
I've always steered clear of using my Verizon, Comcast, Cox, etc, email accounts for anything because what happens when I move and/or no longer require their service that my email address is attached to?
It seems that ANY advancements ANY of the other major email providers (hotmail, yahoo, etc) have added were in response to what GMail decided to offer on their own.
I've owned a BlackBerry since 2007, and now own an Android device, and the ease to which the contacts and calendar sync from web to either type of device is fantastic as well. I haven't had to worry about backing up contacts in a long time.