The Sea Horse is clean, comfortable, and nicely decorated, with all the amenities and then some. The back patio is a wonderful, private get-away, perfect for eating your breakfast in your PJs. Steve, Viviane's husband, was around when we got there. He was a gracious host, showed us where the laundry was (it's in the blue building next door), and let us know we could use the beach boards and kayaks, in addition to the beach chairs, toys, and umbrella. There were bottles of sunscreen and bug spray (you might need it on the patio) in the apartment; dish soap and some kitchen basics like oil and salt and pepper, and aluminum foil; and shower gel, tissues, and plenty of clean towels in the bathroom. The bathroom looks recently renovated with lovely white marble tiles and a new vanity. There was plenty of space in the medicine cabinet for stuff for the three of us. The air conditioner works great and there is plenty of hot water (actually, it gets really hot, so be careful if you have children with you).
The apartment is in a great location - 2 blocks from the unguarded beach. If you want guards and facilities (bathrooms and showers) it's a pleasant 10-minute stroll down to the Pier. The benefit of being about 9 blocks from the pier, and all the restaurants that go with it, is that the apartment is SUPER quiet. You can't hear any of the music from the restaurants and you don't get any obnoxious party-goers walking past your windows at 2am.
Overall, it was a good place to stay in Deerfield. Steve and Viviane were responsive to all our questions and made sure we had everything we needed for a pleasant stay.