As an experienced DK2 and head tracking user... aka. I have no life
Firstly: Head tracking.
The head tracking system clips onto your cap or headphone band and a little camera sits atop your monitor.
With non-linear curve settings, slight head rotation is magnified in game such that an experienced user barely needs to move his or her head to effect a much larger directional change in the view point, rendering the POV hat completely obsolete. Quite literally within the hour it becomes second nature, and you end up finding yourself doing amusing "Matt Parkman" head turns in games which don't support it.
I was given a DK2 by a wealthy friend of mine who said it gave him a headache. I have been using it for a couple of months with the killer app: Elite: Dangerous and it seems to suit me in that department. I am able to spend several hours at a time without discomfort. It was a bit heavy at first, but I think I have developed muscles to cope since I started using it.
It quite literally opens up a new dimension in gaming. Sure the DK2 has a ridiculously low resolution compared to my 4k monitor but it makes up for it by having a much "larger" canvas that you have to actually look around to see. You feel far closer to the action, nay, IN the action. Moreover the lack of resolution becomes much less noticeable when actually piloting because your head is constantly in motion and your brain's ability to overcome visual impairment is quite astonishing.
When other people are likely to be around, I go back to playing Elite with my regular monitor. The change is jarring, to say the least. It's like you've lost one eye and are staring at everything from far away. It's a far less convincing experience and honestly, the DK2 has quite literally ruined non VR compatible FPS and space shooters for me, even with head tracking.
I, personally, was impressed enough with the DK2 to pre-order the v1.0 product. I have since put the DK2 up for sale on Yahoo Auction and it sold the first day for 82,000 yen, just 10,000 or so less than what I will pay for the v1.0 when it ships. So it looks like the kit will certainly hold much it's value post purchase, at least for some months while numbers are limited. In fact, one could say that the waiting list is so long that you might actually be able to resell it at a higher price than you purchased it for if you decide you don't like it.
Head tracking. Fantastic solution to in game POV. Definitely the best bang for the buck. feels far more natural that you'd think.
VR: VR won't blow you away, but if you have GOOD software tailored to it, it will literally add an extra dimension. It's a case of how much money do you want to invest/waste now when you know that within two years a better bit of kit will come along.