I don't much like the exclusivity clause, and the impact on authors who don't sign up to that. It feels a bit like handing your wages to a bank to manage, but the bank doesn't care about you, oh and also if you don't hand your life savings to that bank they stop bothering to maintain your credit history.
Amazon's hourly list of the top 100 "paid" Kindle bestsellers appears to be under the steadily growing influence of Kindle Unlimited "checkouts," which are counted as part of paid sales. In this morning's check, 45 of the top 100 titles are also available through Kindle Unlimited -- and 24 of the top 50 titles. Amazon Publishing's own titles still appear to be benefitting the most, and self-published authors who are not exclusive to Amazon (and therefore not part of KU) seem to have lost the most bestseller slots. (We still have no idea whether this is affecting actual paid sales, or just bestseller list slots.)