They don't have to do powered descent from orbit for this to be worthwhile. Just doing powered descent for the recovery of the first stage would be a huge win.
I'm sure they'll start with just the first stage, but you can't just do a powered descent - that would leave it in the middle of the Atlantic ocean. It has to be a return-to-launch-site maneuver and landing, which is what you see in the video linked to above. At the point where the vehicle does a 180-degree turn (referred to as a "death swoop" by rlv enthusiasts), it's going Mach 6 and is 1000 miles downrange. That's hard.
Bezos, or his handlers anyway, can be pretty outrageous with this kind of stuff. Water landings of VTVL's have been talked about since the 1960's by various people. It would be pretty ridiculous if he was granted the patent for it.
http://www.space.com/13140-spacex-private-reusable-rocket-el...
I'm sure they'll start with just the first stage, but you can't just do a powered descent - that would leave it in the middle of the Atlantic ocean. It has to be a return-to-launch-site maneuver and landing, which is what you see in the video linked to above. At the point where the vehicle does a 180-degree turn (referred to as a "death swoop" by rlv enthusiasts), it's going Mach 6 and is 1000 miles downrange. That's hard.