HoloLens is first a MR device; let's see how it differentiates itself from other AR/VR experiences available in the market.
In a typical VR device, you will be completely cut off from the surroundings; that means you will not know what's going on right in front of you. Microsoft HoloLens is different in that respect; it doesn't cut you off from the surroundings. After wearing a HoloLens device, you will continue to see, hear, and respond to whatever is going on around you.
HoloLens is a completely independent device--it is not dependent on any PC nor on any smartphone. It's not like any other VR or MR devices, which require physical connectivity to either a PC or smartphone. Due to this feature, it's very versatile and mobile in nature; its user can carry it anywhere like another mobile device.