Until the advent of fly by wire it wasn't very effective. The first large scale flying wing, the YB-49 had major stability problems with the initial design. Latter test versions had small tail fins installed to improve latteral stability, but even that didn't solve the problem. Took anouther 50 years before Northrop was able to solve the problem and built the B-2. With computer controled flight surfaces, those controls are constantly making adjustments that the pilot never even sees to keep the plane pointed in the right direction.
As far as being more efficient, it's kind of a two edge sword. The control surfaces have to do more work to keep it pointed forward, but the upside is that you don't need a tail section on the plane so there is a huge savings in aerodynamic drag being reduced. That makes the plane more efficient overall. Less drag, more speed and range for less required power from the engines.
