First on solo I had no idea what I was doing. Second night on with @phil bottle and it is brilliant fun. Got shot of a cannon, drank grog and got sick. Then put in a bucket and then chucked it over Phil. Twas hilarious. Did some voyages (quests/missions) to kill some skeletons and then had to find the right island for some treasure. Dug it up and brought it home for to collect our gold. Did well not to run into any other scurvy crew so maybe next time will go out searching for the big ships and see if we can take them on.
I can see already where the initial criticism has come to the game about content but I don't think it's made to grind for 7 hours a day to to do the voyages as quick as you can. It's a real relaxing game to play and sailing on the seas looks great. As the ships have a few things going on, it really makes a significant difference if you play in a party. Playing solo I think you'll struggle to enjoy the game as you get some reward out of taking roles such as lookout or checking the map whilst others sail the ship and another changes the speed of and direction of your sail.
I wouldn't say its worth the full £50 from an objective viewpoint, however for the FG value of playing with people here i'm definitely thinking it was still a good purchase. Looking forward to trying crossplay at some point with a few of Xbox people to see how that runs.
Oh, and being able to play musical instruments together is hilarious. Definitely grabbing a beer or 7 when we go sailing again.