The demo is available on Steam. The graphics are very good and the gameplay is what I expected, just different units and terrain and it looks prettier. The demo does not allow campaign play, just battles so I can't comment on it. The sea battles seem interesting, very similar to a game I bought years ago (and didn't like for various reasons) called Age of Sail 2. You'll have the ability to capture enemy ships and put them in your fleet.
I was looking forward to the multiplayer campaign, but as I read it won't be released right away. It will come later in a patch. Not surprising since they delayed the game a few months ago and I'm sure the corporate guys were like "let's get this unfinished game out the doors so we can make money now, not later!" Which from a business standpoint might have been a must do.