Nassau International Airport is the major hub in the Bahamas. If compared to other airports in the Caribbean that serve the tourist industry (North American as well as European), it is fairly run down.
NAS is divided into two separated (withing walking distance) terminals: Flights to the US and all other flights, including domestic. The US terminal is OK and of somewhat ok standards. There's a little souvenir shop, a bar and a self-service restaurant. It could be very packed during the holiday season. Arrive at check-in at least 3 hrs prior to departure. Check-in, security and US immigration and customs, tend to slow down the process of arriving at the gate. Security checks are of the same standards as the ones in the US. Flight delays very likely.
As far as the other terminal: forget it! The domestic (inter-island) lounge is just a room with broken chairs. The intenational (UK, Canada, Cuba) lounge is dreadful, shabby and dirty.
Neither terminal has biz class lounges.