Warhammer is a heavily explored universe, and just when you think it's all been done and then some, another title springs up to change your mind. Man O' War Corsair is definitely a large step away from your traditional RPG / RTS feel and it feels interesting.
The best comparison that can be made is probably to liken it to the pillaging ships part of Assassin's Creed: Black Flag but with less hidden daggers and more magic. Its a little disappointing that you only get to play around with humans in the main, open world portion of the game, but I have a sneaking suspicion this might be altered in future updates or DLC. Being able to hire your own fleet of wizards to zap things from afar while you go wild with a cannon is definitely a good starting point, but there feels like there could be a little more to it!
All that being said, this game is heading to Early Access in a few days (Friday 15th April 2016) and will give you the open world segment to float around and cause havoc in to start out. Later on, you'll have the chance to get your teeth into a bunch of different races and some multiplayer mayhem, presumably after a tonne of feedback has been processed from the main game.
The game definitely seems a little rough around the edges at this stage, however that's more than understandable considering we saw a very early build on the show floor. There's a really solid title on show at the moment, we just there's enough polish given over the Early Access process to bring it up to where it can be a great fun cannon-filled voyage.