IMO, $6/mon is more of a nuisance than a hindrance. One has to wonder, though- why six dollars, as opposed to twenty? I would be just as likely to pay $20/mon as I would $6/mon, if I think that what they're offering up is even slightly better than what than Google or Zoho offers.

So, the problem isn't so much the fact that it's not cost-free, but that it's cost-free but cheap. I don't like cheap.

The fact that it's Exchange puts it way ahead of Google Apps IMO.

I'd like to say that customer service is another huge difference since Google Apps customer service is basically non-existant, but Microsoft's may be even more frustrating because it lures you to think that it exists, but it's horrible.