Far Harbor itself is a sizable bit of real estate, but longtime
Fallout veterans may end up comparing its muggy, swampy dangers to those in the similarly-themed Point Lookout area from
Fallout 3. That being said,
Fallout 4: Far Harbor is able to get more mileage out of the setting. Lurking in the radioactive fog are several of the same kinds of mutated horrors you're used to fighting, but it's mostly marine life you'll be contending with.
Far Harbor introduces special gear to help you put them down. Harpoon guns are slow and sometimes unwieldy, but they pack a serious punch -- especially in V.A.T.S.
Most of the new experiences in Fallout 4: Far Harbor are quite enjoyable because they are built on what the game does best: atmospheric adventuring and fun shooting action. However, there's one extended sequence that leaves all that behind for something newer. Without spoiling anything, I'll simply state that it's a great idea that just happens to be poorly executed. It's unavoidable if you plan on getting through the main story, and it absolutely kills the momentum established by earlier quests.