I just don't see the point in introducing the inefficiency, weight, and cost of gears where the derailleur is a more elegant solution. You need a chain drive, so it may as well serve two functions.

A similar system is already on the market for more than 10 years. See here:
http://www.schlumpf.ch/hp/schlumpf/getriebe.2012.engl.htm

I'm not sure why they are not demoing this with an internally geared rear hub. Seems to be the logical thing to do.....

mid-drive motors for electric bikes, combined with bracket or frame mounted gear switching system is where future insane performance will come from .
otherwise--------the age old gear innovation game will continue on.......and on ...and on......

I think the next, and best step is to integrate this with a dc motor under the crank, with the pedals having an integral freewheel. The objective would be to get the best effect of a pedelec and permit the rider to NOT have to pedal all the time. I look forward to seeing this on the market but at a much lower price point. Three Bill$ is way too high to be a viable aftermarket modification for most riders.

A 2-Speed Patterson Metropolis lower bracket competes with the Efneo with a savings of about one hundred bucks. The chain-ring is not replaceable but comes in two sizes. A major stumbling block is the inherent drive power needed to simply run the gears in high. I got used to 1:1 up front to start from a green light then used high for lightly walking the pedals down a slope. I've had both the Metropolis front and Shimano 8-speed rear systems installed on a bike at the same time. Hoisting that bike onto a transit bus bike rack then up a flight of stairs to get home was a test of strength in and of itself. The Shimano and Metropolis internal drives are re-packable (lighter grease) in order to decrease the internal drive losses that a rider has to put up with.

@juehoe: The system you are linking to 1. has only two speeds---you have to choose at time of purchase whether you want the low gear or the high gear; 2. costs about twice what the Efneo costs (based on a quick google search---the manufacturer is coy about a price list, I wonder why). 3. is shifted by kicking at the hub, a less convenient action than Efneo's cable shifter.

For an urban bike a 3 speed sturmey archer rear hub (for about 1/2 the price of this) with a fixed single chainring is just fine for urban riding, unless you live in some place like San Francisco.

Looks to me like the next step would be to get a Shimano internal hub along with this....and then get a belt drive!! talk about clean quiet nice........I like this!!.....LOL

Well,I don't know butt just for kicks and giggles lets take one of these internal derailleur's in front and a 7-11 speed internal hub in back and now we can get one of those pretty belts and get rid of the chain!!No more grease,torn pant legs!!.....LOL :-)