We came across this article on reliefweb, that gives a good summary of the damage.
On Thursday, 29 November at 15:00 hrs (13:00 hrs local Caribbean time) an earthquake of magnitude 7.4 (National Earthquake Information Center http://earthquake.usgs.gov/regional/neic/) occurred near the island of Martinique – Windward Islands in the Caribbean. The epicentre was located at 14.921°N, 61.264°W. (21 km east of Martinique) at a depth of 145.4 km (90.4 miles). Tremors of varying time lengths and magnitude were felt in other Caribbean islands – Dominica, St. Lucia, Barbados and Trinidad and Tobago. Mobile phone services have been interrupted in many cases, and the tremor was felt hundreds of miles away in Guyana, on continental South America. However, as the depth of the event is considerable, the impact on the surface has been moderate.
This could have been much worse.