You can move and steer simultaneously simply by grabbing the tops of the front wheels. When riding on roughly surfaced roads you will feel the bumps. Your body can get thrown around a bit, but the seat mounting rubbers and the flexibility of the seat itself insulate you from most of the high-frequency vibration so you don't suffer from chattering teeth. The extra rolling resistance is noticeable on rough roads, and you need to steer three wheel tracks around any potholes. Because of these factors, two-wheeled bikes generally do better on very rough and potholed surfaces.
Speed humps can be fun, as it is quite easy to get all three wheels off the road.
You can minimise the effect by leaning a little to the left, to center your bodyweight over the rear wheel. I managed to get a snake-bite puncture on the rear wheel by riding at 20 mph into a 1 inch deep 2 foot wide pothole. I guess most bikes with narrow tyres would have punctured. One advantage of the Windcheetah is that you can remove the tyres and inner tubes from all three wheels without having to remove the wheel first. If you've got a spare inner tube a puncture doesn't need to hold you up for long at all.