I actually use gmail for many reasons, the main one being I can get all my emails even ones addressed to me at my domains all in one place, and can send via gmail's servers, so don't have to worry about setting up mail sending, problems with mail servers going down and so on.

Plus my gmail account is my adsense account, youtube account and lots of other things.

Plus its a Google Service, it's free, it is going to remain free, you won't get them adding charges on after your free trial has expired. So can't really knock it, free and reliable, plus many more features you won't get with paid services.