Interesting . . .
Looks to me like the Liftmatic oven would be ideal for a smaller kitchen as it doesn't take up any countertop space. Normally, a wall oven mounted at conventional eye level will suck up 30-32 inches of countertop since you can't have both the oven and countertop. They can be mounted below a built in cooktop, but that loses the advantage of eye-level access and one might as well buy a freestanding range anyway in that case. With this design, the oven is mounted higher than would be comfortable for all but very tall people, with useable counter space below, but the dropping bottom brings the food down to a convenient level.
The only reason I wouldn't spec one of these is my fear that it would break after a few years and either not be replaceable (if Siemens has problems and gives up on the design) or be replaceable only with another Siemens (homeowners who have to prematurely replace an expensive appliance won't want to buy the same brand again).
A few years ago Sharp made a very neat microwave in a pull out drawer that was just perfect for installing under the countertop, particularly in an island. I never specified one for the same reasons, but if these concepts stay around for awhile I'd love to design them into a kitchen.
Oh, and I do love the names that Siemens is using for this oven: Liftmatic and PyroKlean. I just wish you could order a model in turquoise porcelain with Liftmatic and PyroKlean in nice shiny chrome script under the window!