Is mobile data more reliable than the Wi-Fi at my villa or hotel (e.g., Eden Rock)?

Yes, for mobility and security. While luxury villas and 5-star hotels (like Eden Rock or Cheval Blanc) have good Wi-Fi, it is fixed to the property. A personal eSIM gives you a private, secure connection that works everywhere, on St. Jean Beach, at Saline Beach, or when driving around the island. It is essential for using Google Maps on the island's steep, narrow roads.