I became an owner almost five years ago now. During that time, there were two notable negative changes I saw. The first was very strict (and expensive) guest certificate policies, as noted above. That's nothing other than an attempt to make life difficult for the renters, and honestly I think it flat-out failed, but we are stuck with it. The second is that the cost to trade in RCI/II has also gone up---though in all honestly, the old system allowed owners to rob the space bank blind, and was unsustainable, so it was not completely unexpected.
There have also been some changes to the VIP program, but I'm not a VIP so I do not track them as closely.
On the plus side, over the same time, the online reservation tool has been greatly improved, including real-time inventory management. They have also added the ability to book RCI exchanges online rather than having to call. Finally, there have been some nice additions to the resort portfolio, including adding some Smuggs inventory via WAAM that *includes* owner-access to the Smuggs amenities.
On balance, I'm still happy with my *resale* ownership. And, for the most part, the people around the pool who bought from the developer are happy too---that's largely because they don't know what it would be worth if they tried to sell, but sometimes ignorance is bliss.