It is still a little rough, but the new effects are great!
I'm not sure if this helps, but I've found that if I brace myself as if I'm in a real bobsled (feet pushed against the rests, back snug against the seat, hands holding the bars tightly) that the ride feels much smoother. It's actually surprisingly like riding a real bobsled, as the ice tracks end up pretty beat up throughout the season. I just imagine that it's the real thing, and the experience seems less like a bumpy rollercoaster, and more like an icy adventure!
Does anyone know which of the two sides (Fantasyland/Tomorrowland) is less bumpy?