Been there. Done that. When we were in Tortola, it was quiet, real quiet. We were there at the end of October last year. And to get there, the best option is LIAT...
The best beach in Tortola is supposed to be Smuggler's Cove. To get there, you must drive on a rocky, pot-hole filled road for about a kilometer.
If you are used to Saint-Martin, the dining choices are very limited. We found only a couple decent places.