Just had a look at it. Smallprint: "Credit good for $50 towards
any title and $99.50 toward any CONNECT eBooks
Classics title will be applied to your account."
In short, you still get only $50 in real credit (not a bad thing anyway), but you have the option of downloading public domain books that are free anyway. I guess it is a bonus in as far as it is a convenience since they might be easier to find and better formatted for the Sony reader. But it certainly isn't the same as 3x the credit to buy any book in the store, which is what most people would expect.
Ah, those sneaky marketeers...