Good seafood in Bar Harbor?
Walk up the street to Galyn's. I've never known anyone to be disappointed there. Good food, good service, fresh seafood. Another choice is Maggie's, for the lobster crepes, but that restaurant's a bit fancier (you know, tablecloths). You might also ask if the Lobster Claw has reopened (and where). A friend swears by that li'l joint for lobster rolls and other lobster fare.
If by "Bar Harbor," you mean Mount Desert Island (which often is the case), you should trek over to Thurston's Lobster Pound. It's on the western side of the island, probably a good 1/2 hour drive from Bar Harbor itself, but worth the drive (which is mostly very scenic anyway). Fresh lobster, a great view of a working Maine harbor.... it's the total package.
Thurston's Lobster Pound
Bernard Rd Bass Harbor ME, Bernard Rd Bass Harbor, ME