First, this is a bargain price. I will pay the yearly fee without question. It's essentially like one full free module a month plus Dragon magazine for significantly less than the cost of a single paperback module. The magazines were always a bargain, and this makes them even more affordable.
Second, there is no way this is comparable to the prior free content for 3.5, or even 3.0. The prior free content, while good sometimes, was just never close to the quality or quantity that we have seen so far from the free sample magazines they have put out since 4e started. Nor is it really relevant if something used to be free and now is not, if the something is WORTH the amount being charged. It used to be free to go to all national parks for example, and now major national parks charge an entrance fee (up to $25 for the "iconic" ones), but pay national parks are still a bargain. That seems pretty similar to these magazines (only the magazines, as I said, are WAY better in quantity and quality than the free stuff from earlier IMO).
Third, the quality of the free mags we have seen so far is, in my opinion, equal to the quality of the Paizo-published issues, on an average basis. It's been really good stuff, and if folks doubt that but have not fully read it yet, I strongly urge you to give it a try before casting judgment on it. Of course a long term comparison isn't available yet. But from what we've seen, the quality is top notch.