We use Skype all the time to talk to the Grandkids. When we tried it on the Volendam, it did not work. The connection speed is just too slow.
Is it worth taking a computer, depends. We check email, but that is about it. As I said the connection speeds are slow. If you send images in your emails, be sure to downsize them. Also you might want to write you emails ahead of time, then sign on to send them. The main reason I take a computer is for my photos, both storages, viewing, and editing.
BTW welcome to Cruises Chat.