Have been on the Millennium a few times but don't use the computers, glad to get away from them but looking at the users I would estimate the speed would equate to what you would get at home if you used just a telephone line and no broadband. I get 60 Mps at home I guessmate for the ship 5/8 but others may have used the computers and have a better answer. They do have courses you can sign up for as well as accesss which is in several locations around the ship apart form the IT room(s) themselves and there is a good cover for wi-fi if you take your own computer with you but you will need to register, but all that will be explained if you do this.
We loved the dolphins if you stop in Gibraltar; we took the train to Monte Carlo lovely place but the casino was not as big as we thought it might be; we visited the Piza to see the leaning tower but we skipped out on Florence, we know it is lovely but we are not into art gallaries; we loved Malta and always like to visit there if it is a port of call; most of our other excursions were fine but not worth passing on as what we like might not be to your taste. Hope this helps others may add more of their ideas into your melting pot for excursions.
Apologies looks as though the 'system' has put a reply I made for someone else on yours.