5/5 experience at the Oasis Marigot with my wife this month. Everything from the booking process to the stay itself was wonderful. The villas are located overlooking Marigot Bay which in our opinion was the most beautiful and laid back area of the Island. There are a dozen or so private villas (whole house) and you get one to yourself. There is a shared pool area (very clean and there is an adjacent shower) as well as a private white sand beach beside the hotel. The beach is shared with some other resorts but there is a roped private area just for Oasis guests. Security is good and the staff are very friendly - if anyone is slow to respond it's not because they aren't friendly they are just taking time to understand your accent or you may have spoken very quickly. There are locals on the beach that will sell food, drinks, goodies but you can politely refuse. There is also a very good restaurant on site called DooLittles which was where the original movie of the same name was filmed. They have a happy hour (2 for 1 beers) and the bar has nice cocktails. There is also a hiking trail accessible behind Villa 10 which the resort maintains. It's all uphill (45 min round trip) and has stunning views of the coastline and bay + sunsets. If you are a good to intermediate hiker I'd highly recommend doing it at least once.
You can only reach the resort via a ferry which runs 7am-11pm. If needing after hours you can let the resort know beforehand and they'll make special arrangements.
The on site manager Irwin is a delight. Extremely friendly and made our whole stay super enjoyable. I am sure Miranda is very nice too but we didn't get the chance to meet her. You can book activities and services through them such as snorkeling or water taxi. You can also arrange for them to prestock your villa with groceries before you arrive. The nearest Massey supermarket is 15 mins away. The booking staff/team are not the same as the on site team but were also very responsive and pleasant to deal with via email.
Parking for the resort is in a gravel parking lot behind the Marigot Police station. Pickup/drop off via taxi is right at the dock for the ferry that takes you to the resort.
Overall we had a wonderful time and highly recommend Oasis Marigot to anyone looking to visit St Lucia.