The enemy ships have better turn radius, faster firing cannons, and auto-aiming cannons. This inflates the difficulty in a rather obnoxious way. I also don't like the fact that you can just pull a reverse out of nowhere. I think games should improve on the past, but this is a far cry from the feel of combat in Sid M's Pirates.
Edit in Response: It's not about the difficulty as much as it's about the differences between enemies and players. It just doesn't feel satisfying as a "ship combat game" when the ships don't act like ships.