Hmmm - didn't even rate a 'welcome to CF'.
After making the journey, I can see why there weren't many comments about the north shore of Puerto Rico
- nobody goes there. We saw only 2 non-commercial boats in 3 days, and only about 10 boats/ships total. To answer the OP's questions - Arecibo is a nice little anchorage, with room for just a few boats, but no problem, because you'll be the only one there. (The local fisherman and the maritime police both wondered what we were doing there - nobody comes here). Also, the north coast is usually pretty rough according to locals, and the NWS forecasts are pretty worthless (predicted 12-17 kts with 3-5 ft ended up being 23-28 kts with 6-8 ft - I'm glad we were going downwind).
The west and south coasts are a little more travelled by cruisers and daytrippers, but still pretty quiet. A lot of nice gunkholes.