While these new features are really cool, very few people will actually
need to use them once they take the time to become more familiar with how their Phantom works and what needs to be done to fly safely.
The "auto follow" feature is just a fun way to impress a friend for most people, but many will find they don't actually
need to use it. The "active obstacle avoidance" will probably turn out to be most handy when avoiding obstacles as the Phantom returns home. Again though, most people will not
need that feature since they
should be setting the properly RTH altitude prior to takeoff.
For those reasons, I would not recommend buying the Phantom 4 for just for the new flight modes and obstacle avoidance. However, there are
many other features/changes that do make it a great buy
(especially for people who don't own a Phantom now).