When I first got GMail, but when it was still exclusive, I invited my favorite cousin to join it. I told her about all the features, and that it's still free, and she wanted to know the catch.I explained contextually based ads, and she said "no thanks" because she freaked out about privacy. But is it really a privacy concern?
Google was the only company that refused to turn over search records, due to its lack of constitutionality, but more importantly, nobody is reading your emails.
I get like a hundred a day, and so do millions of the other tens-of-millions of views. Nobody has time to read even just a couple of them. More importantly, is your email really that interesting? Big thing to bear in mind, no matter how grand or lousy your email is, it's no more or less secure. It's just that Google's GMail is free and honestly amazing.