The only downside of buses on the French side is in getting to Orient because you have to walk in from the highway. Other than that the bus service is perfectly fine and is in fact a great way to experience a little local culture. Marigot and Grand Case are well served although will require a transfer at some point. You might have to wait all of 5 minutes for the connection. Meanwhile drinking and driving on the French side can land you in a world of trouble. And alcohol checkpoints are common.