I've tried a hololens and it's pretty amazing. Yes, the field of view is bad, but the tracking (6 DoF tracking!) is absolutely rock solid. Better than a Vive or Rift, and it is using inside-out tracking. There's also no perceptible latency (again in my unscientific head-shaking test I'd say it is slightly better than a Rift or Vive).

Magic Leap are going to have to do something seriously amazing to beat the hololens, especially when they inevitably upgrade the FoV.