This mosaic was the best planned one I've done so far. I would recommend walking the majority of the mosaic and driving 11 to 15 since they're far apart, but you could walk, bike, or drive the entire thing. Driving might be tough in downtown Raritan if you're not familiar with the area, and you can't walk across the Somerset Circle to get to numbers 12-14 (you can walk/bike across 202 at 1st Ave, but it does add some distance to the route). It took me about 4.5 hours to complete, but you could definitely do it quicker. All in all, I'd highly recommend this mosaic.
Freylinghuysen Arboretum is the only part that isn't open 24/7. Try to visit the railroad museum in the afternoon or night when staff isn't around.
This mosaic was all over the place, and there wasn't really much thought put into the route. You end up visiting the same places multiple times driving back and forth, and you even end up in Parsippany for some portals on 11. Not something I would recommend to a random visitor.
I understand that this was made when there were less portals in the area. It's time for a new, better planned mosaic in the Hanovers.