The Rhine in front of Iffezheim is higher than the surrounding area. That creates a nice perspective. On the dam: gravel. Between the dam and the street the Rheinnebengraben, which can be crossed over different bridges. The road is (of course) asphalted, little traffic and leads past the edge of the floodplain forest.
You have the choice between
a) dam: pedestrian, great view, gravel, sun, now and then a bench for a break (sun!)
b) Road: some cars and motorbikes, birds mottled, asphalt, rather shady, now and then a (digger) lake for a break (shade!)
The bridges over the Rheinnebengraben also give you the opportunity to switch back and forth.