It's an Interstate; you won't have any more steep grades or low bridges than on any other Interstate (and less than some). Generally a nice enough road, a little irksome going through Springfield, MA due to traffic and such but not too bad. Beyond there traffic is generally not an issue in the least bit. The scenery is pleasant, and indeed quite pretty in some areas. Around I-89 there are a couple of miles where reasonably strong cross-winds are not uncommon; nothing at all unmanageable, but something to be alert for.
Rest areas, with facilities, I think there's just the Vermont Welcome Center (which is very nice) and one at Bradford not far from US302 when going northbound, and a rest area just south of I-89 southbound. Fuel is reasonably available, although there's not a station at every exit that would easily accommodate a large fifth wheel. It's not as though the entire route is all that long anyhow; you likely could get all the way from the southern MA border on a single tank.
