I just came back from Zemi. Not much to add to what others have said already, except food. IMHO, food is pricey pretty much anywhere you go in Anguilla. I didn't think the Zemi's food at 20knots is a higher other than others. The only "cheap" food I found was Blanchards Beach Shack in Meads Bay. They also rent out beach chairs and umbrellas for $5 a day, very reasonable prices. From Zemi, you need a car to get there.
https://blanchardsrestaurant.com/


As far as car rental, I went with Andy's Car Rental, as I needed an 8 passenger minivan. The one offered via the hotel is Land Cruiser, but 3rd row in Land Cruiser is tight. If you don't need an 8-passenger one, just go with what Zemi guess services will offer. Prices are about the same or just a little higher.