A bastion, Panos, is a projecting part of a fortification, so I'm not really sure this set is a bastion. I would have expected the bastion to be on the sea side projecting out so that it's guns could cover the harbour area from attack.
The walls look pretty minimal in detail which reduces their appeal and because of the minimal detail do look Fisher Price-like. The curved walls is good practice as a curved wall is stronger than a flat and a curved corner is stronger than one where the walls meet at an angle, e.g. 90 degrees.