This is the largest of the resorts that we have stayed at on St. Barths. You do lose a bit of the charm of the smaller resorts that are abundant, although the Guanahani doesn't really give anything up facilities wise. Service is good, not great. Food is good, not great. Rooms are excellent, as is the beach setting. Pool wasn't really set up for use by families as it was bar side and didn't feel like the right place for a family with children.
But forget all that the island is spectacular. Great food, great shopping, and not too crowded. Very American friendly (unlike some parts of Paris). Be sure to rent a car, and be sure to drive carefully on the steep and narrow roads. You will get lost a few times if you venture out to the many restaurants, but it will be worthwhile. Did I mention how great the food is there?
The beach offers a constant breeze that keep you comfortable at any temp. And you really will lose sight of the hustle and bustle that you may regularly feel off the island. We found ti very relaxing and will return to the island soon.