Discover Acadia National Park, 3rd Edition includes the 50 best hiking, biking, and paddling trips in Acadia for all ability levels, including hikes up Cadallac Mountain and cycling trips on the Park’s popular carriage roads. This completely revised edition includes five new trips and the most up-to-date information on where to go and what to do during a visit to New England’s only national park. First-time visitors and veteran explorers alike will enjoy this comprehensive guide to trips on Mt. Desert Island, Isle au Haut, and the Schoodic Peninsula. Perfect for a day trip or multi-day excursion, this guidebook will reveal scenic bike paths, cobblestone beaches, glacial ponds, granite peaks, and ocean-side cliffs.
Overall this is pretty good and worth buying. The downsides are a.) that it is fairly old (but it still seems mainly reliable) b.) it really only contains information about hiking, biking, and kayaking / canoeing routes so if you want to know about restaurants, shopping, which tour guides to book the kayak trip with, etc. you won't find this helpful.
But like I said this is a fine option and since there doesn't really seem to be a better one it's worth purchasing prior to your acadia trip.