I've just noticed today that my facebook page barely reaches to 3-4% of the total likes I have on my page (vs. 20-30% few weeks back).
That sucks because we wasted some money to bring people to "like" our page, and now facebook wants us to pay to show our content to these "likes". But yeah, they are a business as well, and eventually can do whatever they want. I don't really think this move would bring people to waste tons of money on ads, but we will see. I'm done basically investing in Facebook after this move - it makes no sense anymore unless you have a variety of products, and you can get your investment back very shortly after (which I probably can, but I can do it without facebook as well).
All in all, facebook is still the "cheapest" platform to advertise your website/products/services compared to Google AdWords/Magazine/Newspaper/Banners on different websites.