Budapest is a difficult place to board ship as the location can change on short notice by the Harbour Master. We found that even with the exact location of the ship the taxi driver whose English was very limited (and our Hungarian non existent) had difficulty in locating the ship. We would recommend that prepurchase of transfers to the ship is a better way to go.
The included tour is very good as it covers most of the city sights. We also used the funicular at the Chain Bridge to go up to the castle precinct. Tickets are inexpensive and the views were fantastic.