Well, I wouldn't go that far. I've found Griffon and Apollo's Chariot to be smoother rides than Alpengeist. But I don't think Alpengeist is all that rough, either.
I sort of agree... while Alpengeist is easily one of my favorite inverts, it does have it's moments. But then again, so does every other old- school B&M.
I think the only moment is the cobra roll, but even that isn't horrible.