OK, SB I agree it does look ugly.
I guess they are going for lots of body lift; not the sort of "lift" you may be thinking of
but by making the fuselage top curved and the bottom flat (i.e. like a wing) they will be getting a lot of lift from a part of the plane which is otherwise a waste of space (except you need it for the people to fit into) and which would otherwise just be a large frontal cross-section which needs to be dragged through the air.
In turn, you don't need so much lift from the wings and they can be smaller... less drag etc.
This is a very old technique but is not so effective on something long i.e. a 6+ seater. It also needs composites to do the curves, unless you spend a lot of money on press tooling or 3D CNC setups like they do on airliners.
Recently I went around an EADS factory and it was interesting to see the order of magnitude gulf in the tooling investment between passenger and military jets, and a TBM which sells for a mere $3M or so. The latter is made almost entirely from 2D curves (a flat plate bent over, basically).
Two big problems with composites: it can be very expensive or impossible to repair hangar rash, or accidental over-stressing e.g. a tiny crack around a door hinge.
Overall, composites are rarely lighter than aluminium unless you go flat out for carbon fibre for everything. But none of these companies are going to invest in the tooling to make these things out of metal.
I'd like to see the MTOW. We are not talking about £1000+/hour DOC on these, or spending so much money on fuel you may as well employ a couple of ATPs to fly it for you (which is true for most exec jets). For Europe, the 2000kg mark will be very important; much more so than on a twin jet. We know that Diamond have already missed it, and not by much which I think is a very bad mistake.