REFLECTOR: Speedbrake, descents, and shock cooling.

[Lawrence Epstein,MD]

How do they affect the characteristics of the plane?  Does it allow for
a more steep decent with lower airspeeds (like a flap)?  

It does allow for more steep decent @ slower airspeeds, but it does not
do that the same way as a flap. Flaps increase lift and therefore
increase drag as a byproduct of increased lift. A speedbrake only
increases drag without adding lift, therefore, it will not change the
AOA @ a particular airspeed/rate of decent/CG/weight.  A well
designed/located speedbrake will not change pitch angle.