I think WP.com should make it a lot easier to find the pricing for the upgrade features. The best would be if the prices were directly on the main "premium features" page that summarizes all of the paid features: http://en.wordpress.com/products/
Right now, there is no explicit direction on how you can find this information, only prompts to sign up for a free account. This is very frustrating. Only after a fair amount of searching through the forums and support site did I learn that I needed to sign up for an account before I could see the pricing. And even if I had just signed up anyway, it wouldn't have been 100% clear where to find the prices unless I had spotted the "Upgrades" link on the blog dashboard.
Since putting the pricing right next to the page that describes the products is fairly obvious, I'm assuming there was some decision made to put this information behind the registration wall? Whatever logic went into that, IMHO this is the wrong thing to do and makes it harder on people who are interested in the service. Just tell me the prices!
At the very least, put a note on that page saying that you can view the pricing options when you sign up for free. This direction would still be helpful even though the more direct option would be better.
It is just annoying and feels shady when companies hide their pricing. It feels weird when a company like Automattic does something like this, when all other indications are that it is very forward-looking and customer-focused.