The visuals are my only gripe with this demo, because everything else is FUCKING AWESOME.
I felt real clever when i checked under the sunk boat and found another revolver.
This format of riding a boat and stopping on sort of "minilevels" works great I think. It would be interesting to see a slightly more open map (not like a massive open world, but maybe a level that isn't completely linear).
Going back to the graphics, they're the only think that doesn't click with me, but maybe these are just programmer graphics, idk. But if I were you I'd focus on either the simple lowpoly stuff or go full into the 2d sprites