How smooth - or not - was the ride? Did you feel every tiny bump and crack in the road? Aero-focussed road bikes don't have a particularly good rep for vertical compliance, and I would imagine that a tri-bike would be even more jarring.
It's a good thing I don't have any fillings, or they'd be gone. I found it especially harsh coming off my front-suspension cushy tire mountain bike.
Some other observations...
1. The bike hates slow speeds. I can crawl around on the MTB with no problem. The tri bike, no way. You need speed, and the more, the better the bike feels.
2. That said, at any speed, the steering is a hair trigger compared to other bikes I've ridden.
3. Riding on grades felt super odd. I noticed the slightest down grade as the bike would pick up speed so easily. However, I barely noticed slight hills that probably would have required a shift on the MTB. The power transfer is so efficient.
4. I had to be very conscious to look far ahead. The MTB is like driving the Highlander. You're upright and naturally see far ahead. The tri bike requires you to look. Of course, riding it all the time it would become second nature, but it was odd getting off my bike onto that one.
5. There was a decent stretch of asphalt trail that ran parallel to the road. It was funny traveling quite a bit faster than the flow of automotive traffic.