GMail is part of Google's world domination plot. I should say plan, rather than plot, as there's nothing secretive about it.

I moved entirely into GMail for a couple of months in spring 2008, then moved back out again. Its continuous encouragement to never throw anything away (just archive it), and its near-insistence that I include the full quote of any message I was replying to struck me as far more in their interests than mine, so I bailed out, back to a system that allowed me a little more control. That, and the relative difficulty (still!) of finding a reliable wireless connection in country backwaters like, oh, Toronto, made it less than perfectly usable.