It shifts like it's being rear-ended because there is clutch fiber in the transmission that is sticking the valves in the valve body. this requires the pump to build more pressure, and instead of the valves moving freely and smoothly shifting the transmission into gear, they release suddenly, allowing the clutch pistons to slam the clutch discs together every time the trans changes gears. I would go so far as to say this car in particular is doing much better than it's american counterparts, since it probably has never been rebuilt. most US trannies are rebuilt every 60-150,000 miles, depending on vehicle/trans/driver. I know your uncle's cousin's brother has a 1976 ford truck with an auto tranny with 350,000 miles that's never been rebuils, but trust me, for every one of those there are hundreds that didn't last over 125,000.
I've been building trannies for 13 years, I just rarely do Hondas because folks in my hometown haven't been buying them long enough to wear them out.
I also like the prospect of being able to stage my boost off the line with the torque converter rather than by slipping the clutch