IMHO it's very easy to get started. It's a lite sim. There are nice tutorials, very good and not so long (50 pages maybe) manual. The game is heavy on keyboard shortcuts so need to learn these but after playing tutorials you should know all of them. There are nice single missions with lot's of randomness so you can play them many times and learn stuff before diving into the campaign.
I also strongly recommend watching tutorials and streams from Jive Turkey on YT. He's done tons of them since release. He's an ex Navy (subs to be exact), knows his craft. His commentary is very informative. I still watch it regularly. It's a huge help for beginners.
https://www.youtube.com/channel/UC9bMgCQyFNaMPsK9GtzM5dQ
