let me see if i can give you a quick response.
we are lucky enough to have lived our whole lives in this beautiful state, and dh and i have gone to bar harbor thousands, upon thousands of times, going multiple times a month, growing up i was lucky enough to have lived 15 min from the heart of bar harbor.
in fact dh and i just got back from a romantic long weekend, staying at the bar harbor inn on the ocean.
now we would go in march for a day trip, but we can drive there in a little under an hour. on the coast of maine in the middle of winter (yes march is still mid winter in our state) you are not going to find many places open. a few motels (nothing to romantic) for the snowmobilers and a few every day places to eat. nothing fancy. this area especially hunkers down from oct to may. in fact all the stores in the village were having their annual 50% off closing sales. (great christmas shopping!!) also note that most of acadia is shut off at this time of year for safety reasons, only a few parts of it are open. if you wanted to snowshoe or cross country then you could get around a few more parts if there is enough snow, but again this time of year it could be just MUD, lots and lots of MUD, lol. you would need to pack for any kind of weather from it being snowing and in the 20's or colder to raining and in the 50's (or as we call it sweatshirt weather, lol).
so the weather can go all over the place, not many places to stay, and really not much to do for activities. now if you really want to see what the true talk is of mount desert island, i would wait until may and come then when spring is starting and the village comes to life. the shore path opens up, and there are multiple things to do in all areas of interest. i would say go for it if you lived closer, and it wasn't as far of a trip but being you are 3000 miles away i would wait until it was more of what you would expect.
if you want to know anything more feel free to pm me!