Quick feedback, the road from Imbert when turning right off the PP to Santiago road to El Estrecho is pretty bad, with bikes it's like those computer games as you try to avoid potholes. From El Estrecho to Luperon and La Isabela (the historic Colon place) it's perfect. But I still can't believe after all these years that I visited last, that piece of 400m or so road going down the hill to Luperon port where all the boats are, is still not asphalted (shame on you DR gov.. !).
From La Isabela (historica as they refer to) to Villa Isabela no tarmac and then you have two rivers to deal with, again terrible road but the rivers are another story. The first one is quite big (the huge bridge, long destroyed and left like it was bombed in a war), they tell me when the water is down SUV cars can cross further up the river, but bikes have to go one by one on a small raft and a guy pulling it along in knee/waist high water for 50p each. First it looks scary but not as bad as it actually is (well, not sure if you want to risk your US$10k Harley though). You and your bike are at the mercy of 6 large plastic cans !
Second one is rather a stream, and even my buddy on a pasola managed it, you just cross the water yourself, though no guarantee how it will be with more water, even now we got wet up to the knees trying to balance the bikes. (I probably backtrack to Luperon and Estrecho if I have to do it again).
Now from Villa Isabela to El Ensanada is a good road, with many villages and huge newly built speed bumps, watch out for people and cows and those bumps, but it is a nice ride. From Ensanada to Punta Rusia no tarmac again for a 2 or 3 kilometers stretch.
Not much to write about Punta Rusia, the beach looks good but has some weeds and rocks for swimming and zero visibility for snorkeling (I think the sand is like a fine powder and floats), mainly people come to go to the Cayo Arena island, not much else there. Some hotels on the beach and lots and lots of mosquitoes ... (I had never had so many red spots on my leg, I usually don't have these spots from mozy bites, must have been some super types - lucky we had mozy nets for sleeping).
Back to Villa Isabela and going through the other (side) road to El Estrecho, the road is better than El Estrecho to Imbert, but then again watch out for some nasty holes there.
Just also mention a quick reference to Miamon to Puerto Plata stretch that after 5 years still not finished, I reckon another 5 years in order - same theme around these parts with road construction....