It's definitely more gameplay than not gameplay. Most of the time, you are steering your boat, exploring, trying to dodge giant underground crabs and pirate ships, fighting enemies with their quite original combat system (so far I like it, though it was confusing at first and I'm not sure how it will change at higher levels), trying not to get lost or run out of fuel or supplies, and watching out for bats. The FL-style story is what takes place when you're at port. There's a limited amount of things you can do at port (though hopefully this will be expanded quite a bit), so you don't spend a whole lot of time there.
The game doesn't progress terribly fast, either. The boats all move pretty slowly, and you have to spend a lot of time going from place to place. You can make money by selling reports of other locations to the authorities in Fallen London, or by loading up your cargo hold and trading goods, but neither of these will make you rich very quickly. Improvements to your boat are quite expensive, as are improvements to your lodgings, so without cheating it would take a long time indeed to get through all the content. Actually, I'd like to see more ways to get money a little more easily, because what with having to refuel and resupply pretty often (and spend money reducing your terror), it makes it nearly impossible to make any real improvements.
I haven't seen any Let's Plays released yet, so maybe I'll do one to give people a preview. Anyone know if they've specifically forbidden making videos of the game or anything like that? I don't want to piss them off, but it seems like something that might be in demand.
EDIT: Does anyone know if there's a way for those of us who pre-bought the game to get it on Steam?