Okay, there are plenty of people on this forum that have been on river cruises and can answer this question. Why so quick to assume an answer is not available here?
If the lower level cabin is what you can afford, then go for it! Some report that if the cabin is at the rear of the ship it can have more engine noise than those at middle or front. While cruising, there are plenty of public spaces to enjoy that floor to ceiling view, either in one of the lounges or on the sundeck. While in port, if your ship is double berthed, which happens frequently in river cruising, those big picture windows in 1/2 the cabins are useless as the drapes must be drawn.
Having the big window/french balcony is nice, but you should be able to have a great cruise even with the smaller window at the top. The cabins are the same size.
I don’t think noise from above is an issue. It is either other cabins or the dining area where usage is limited to mealtime and you will be out eating anyway.