I made another thread about that too, simply explaining why I thought the Plugin Description was unclear:
They should tell you right up front, in plain language: When you go to view your stats you actually go to your WP.com Global Dashboard to view them.
The API key to activate isn't surprising and it is mentioned in the requirements -- everyone has done the same thing to activate Akismet. But with Akismet, your spam admin is still within YOUR wordpress on your domain, you don't have to login or surf to .Com
For me at least, once I logged in the first time, it hasn't been a problem. It's easy. But it was surprising.
@thesp2, You need-not keep a blog on .com for this plugin to work (if you delete a blog on there, no problem). You just need an account.