If with lurches around you mean its slower rotation, that was part of the idea behind it.
As far as I understand, first of all, due to the additional rotation axis, you get more spray directions and thus more coverage.
Second of all, you get soaking time. It basicly is something like 5 seconds of soaking, 2 seconds of spraying.
And, last, you get more contious spray. You get like 1-2 seconds of continous spray for one area. Basicly the principle: 'If you rinse by hand, you don't pulse your tap on and of in half second intervalls, you keep the tap running.'
But really can't see any of this makeing a big difference.