$400.. wow it might cost that much.. But not to me. Who is going to buy this POS. Does nothing.

I don't believe with the current design the technologies available to produce a descent image, work well with finger gestures, hold a charge for very long, or keep from breaking regularly. Someday soon I believe it could work, within a year or 2, just not right now. I could be wrong & I would love to be wrong on this because I really like the idea & will get one someday when they do come out.
Also, the video on their website is misleading in that it looks like they have already made one that works, which is not the case. They are raising money to build a prototype which is where they are going to find out it's not so easy (YET).

I don't think this will work for two reasons:
1) Projectors need low light to work, it just won't work outside without some serious power pumping or of the device. To see the screen outside I would expect the battery to last 2 minutes.
2) Arm hair, surely there is just going to be too much hair in the way. At that angle, every hair on your arm is in the way, just look down your arm at that perspective and you'll see what I mean. They will have to sell this device with razors so you can shave your arm before each use.

People need to look at Kreyos. Promised so much less, and got so much more funding and failed. This is a good use of animation, and will likely get no further than a You-tube video.
Just the optics needed to make an image, from a curved band 12mm (say half an inch) that can project down onto your arm and be clear and in focus is daunting. Ask NASA if the stereoscopic imaging on those Mars rovers was easy, this arm band trick will be more problematic.
And Nummitz, did you not see the 500m extension cord for the cooling such a powerful light would need?

I call bullshit!

Ehhh - and also people with dark skin ... it wouldn't work well now, would it?
Sorry, not buying it.

This is what CAN and can NOT be done by December 8, 2014: - Tiny accelerometer: NOW - Tiny Bluetooth Low Energy: NOW - WiFi: NOW - Memory Card + ROM: NOW - Vibrator: NOW - MicroUSB Port: NOW - LED: NOW - Button: NOW - Flexible wrist band: NOW - Tiny Processor, good enough for crappy movement: 6 MONTHS - Tiny Processor, phone-like quality: 10 YEARS - Pico Projector, crappy resolution and low brightness: 1 YEAR - Pico Projector, HD quality visible in daylight: 20+ YEARS - Tiny Proximity sensor long range: 2 YEARS - Tiny Battery, good for crappy processor and crappy projector: 10 YEARS - Tiny Battery, for phone-like processor and HD projector: 20+ YEARS
Overall estimate: BULLSHIT

Video is faked, tech isn't there yet, total vapourware.

At the end of the summer some white bits are always more interesting than others. No prizes for guessing which category this is in.

It work because he no have hairy arm.