The only downside to Gmail is the damned "on behalf of " messages.

I use the google Apps version of so I can send emails from my primary domain. However, with multiple domains, its critical for me to be able to email from any of those domains. Gmail causes outlook clients to receive "On Behalf of " before my email address when I'm sending from emails other than my primary domain. Even though I have those domains also going through Google's servers.

Its a huge pain. Yahoo plus is better in that regard. Although, I really really prefer Gmail though.