What is the D&L like south of New Hope?
Assuming you mean the PA side, since you said New Hope. It's fine.
Both sides are fine, actually, until you get past Washington's Crossing. The DR canal
through Trenton is quasi problematic. I was never bothered once in 2 years of commuting through there, but I did eventually give the route a miss entirely, since it added 6 miles to the ride.
It's been years, but right around Mulberry, I would jump off, ride Brunswick to Southard, and get back on the path around the War Memorial; the section wasn't "bad", but if you zoom in on Maps, you can see that it flips back+forth between sides, and on top of that, it's not really "scenic". The Canal in Trenton disappears for 3 blocks (you can see that on Maps), and then the stuff that is there is literally a concrete river. Once you get back near Cadwaladar Park, it turns back into 'the canal' again.
IMO, skirt Trenton entirely unless you want to see the War Memorial. Hop off the canal in Lawrenceville, and head out towards the Brearly House. It's a nice little gravel path through the swamp. Follow the path that Bristol Myers put in out to 206, follow that south to Eggert Crossing. Make a right onto Ewingville/Upper Ferry. Follow to Scotch Road, make a left. Follow until you hit Parkway/West upper ferry, and make a right. That road will eventually dump you out onto the canal path, about 0.25 mile from Scudder's Falls.