"It all sounds positively dreadful to me."- well, with the examples given, I agree...
Walking down the street the integrated GPS will allow you to identify persons walking past you in real time, via pop-up bubbles and avatars hovering over them. People could even customize their avatars to send cosmetic enhancements to other people's displays, such as digital costumes or masks. Games will take on a whole new meaning when alien creatures are imaged directly on the real landscape, and you have to defeat them with virtual weapons, and your own physical stamina is put to the test in a real environment!
Those examples are at best frivolous, and at worst disturbing.... but consider the applications that could be valuable...
You could look at a building and 'see' the pipes and wiring in its walls, see the exact dimensions....
If the device is outfitted with thermal imaging you could 'see' hot-spots in wiring, or see in the dark, or see through smoke and fog...
If linked into an MRI map of a patient, a doctor could see into a patient before making an incision- call up vital statistics on the patient immediately... has that mole changed since the last visit? Just call up an image from the last visit and overlay it...
There are countless practical applications....