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.
Yes, very low bridges on the Lake Ontario State Parkway. And no commercial vehicles IIRR. Sometimes we'll take 104 & Rt 3 for a change of scenery when going from Rochester to Watertown.
According to my trucker's atlas, the only low bridge point on 104 is near Niagara Falls, 0.1 mile north of NY 182 (11' 0"), otherwise, 104 is a ok truck route for semis
Now that they have finished rebuilding the road west of Oswego, the construction isn't bad, however until they pave in the city (Oswego) it is a mess. While longer & narrower roads, following closer to the lake on 104A (part of the Seaway Trail), etc is more scenic. 104 through Rochester is where you will hit the most traffic...