The parts of it I'm at all familiar with (mainly Rochester and west) are not bad, not super slow but you do go through all the little towns along the way and so it's not exactly quick traveling. I don't recall it being exceptionally scenic, nor an eyesore either. Usually I go on NY 18 and the Lake Ontario State Parkway, but the latter road would not be good with a 5er due to some fairly low clearances; and besides, it's quite rough in areas. (Unlike virtually every other parkway in New York, noncommercial trailers and RVs are not forbidden from using the LOSP.)
Stopped traffic shouldn't generally be a problem except possibly through Rochester if you hit rush hour. Even during rush hour Rochester traffic does generally keep moving pretty well.