The satellite will break up into many pieces, perhaps a hundred or more, on re-entry. The heaviest piece will weigh about 300 pounds which is roughly the weight of 3 average sized humans.
Several large brightly glowing pieces of junk and dozens of accompanying smaller bits and pieces will be traveling at a fair rate of knots. A veritable display of fireworks in the night sky is possible.
With luck it will all finish up in the sea.
A worst case scenario doesn't bear thinking about.
Mind how you go.
UPDATE: NASA says UARS will not hit USA - may fall to Earth on FRIDAY!
UPDATE: Possible time/location, 2300GMT FRI to 0300GMT SAT Pacific Ocean.
UPDATE: Final resting place unknown. Might be in Western Canada or Pacific.