Interesting concept, I think it needs a redesigned frame, a drum gearing system could be installed into the front axle, the seat should employ contouring so the rider would have more control in corners, and the list goes on, but it's a very interesting development. I hope he's patented his "linear" drive, because I could see it being used for commuter bicycles.

Hmmm..interesting concept.
But those forks look like they are hungry for trouser legs and/or leg skin! Rubbing up and down so close to the fork will surely catch on some material or your skin?
Maybe it would be good for very flat lands such as Denmark or the Netherlands, but the lack of gears would not make it so suitable for any hilly areas.
it certainly looks cool, and would be awesome to cruise through the city (not Sydney, where I live and you'd be quickly killed by our considerate motorists) - but I personally cannot see that it is so practical as a daily commuter.
[climbs into flameproof suit] 8-)

I like the idea of being seen by traffic while stlll easier to put foot on ground without the almost invisible supine arrangement of recumbants. As for the single gear problem, any decent e-bike artisan and mechanic should be able to fit a battery pack in that triangular frame's space and fit a hub motor on the rear wheel. The electronics for speed control have been solved for ages.

He should have checked out Cruzbike as shown in Gizmag: http://www.gizmag.com/cruzbike-silvio-recumbent-racing-bike/13024/ or their own site where they now have multiple variations on the theme, including a folding version. http://cruzbike.com/ The version I have, a Sofrider, is superbly comfortable, has all the advantages Lenz talks about (except the weird pedal system) but uses standard components throughout.

George Georgiev also sold a semi-recumbent to support his world record racers. The problems with drive systems like this are well known, and I don't see any attempt to remedy them here yet. At the ends of each stroke, the momentum of the leg is not only wasted, but requires muscle power to overcome. A spring can help, but it needs to be variable to feel good over much of a range. Linear systems that use a crank don't have such a jerky "boxing" motion. There are lots of ways to add variable gearing, a very popular option. This bike also forces the rider to hold the steering steady against power reactions, a waste of muscles and a liability for control.

I think that is a really nice design. I like how compact it is, easier to store / transport in the trunk of cars. It would be interesting to see how others might adapt the design.
Where I live, it is flat (mostly). With that seat, I can see myself riding around a lot which means I would get a lot of exercise. :)

There are plenty of single-ratio regular bicycles out there, but if shiftable gearing is needed, it appears the bike could be adapted to use an in-hub planetary gearbox---in the front hub, of course.

As the designer claims this is a more efficient way of transmitting the riders effort to the wheel.
The Cruz bike mentioned above uses a rotary crank with its inherent deficiencies this bike uses a reciprocating system; THEY ARE NOT THE SAME.
As a proof of concept it's fine but more work is needed.

I think @Bob Stuart makes good points, and also have to wonder how maneuverable this bike would be if steering forces the pedals to swing sideways (with the fork) as well - what efficiencies are lost when my left leg has to reach further than my right leg during a turn to the right?

If you feel the need to be "high up" in traffic and "laid back" try a Dursley-Pedersen. Patented in 1893 but still being made and apart from frame, hammock saddle and handlebars entirely compatible with 21st Century technological advances. Mine is fitted with a 14 speed Rohloff hub gear system and hydraulic brakes. As for comfort; my back thinks it has died and gone to Heaven!