Most people who visit Prince Edward Island do so by car. They either enjoy the drive here or fly and rent a car. Because PEI is small, you don’t seem to get as good a deal on car rentals. Therefore, some people prefer to fly to Halifax and rent a car there. They save the airfare to PEI and often get a better deal on a car rental with unlimited mileage. There are many rural places to visit in PEI and you cannot always get local transportation there. So My recommendation is to plan to travel by car.
If car is not an option for you, There is public transit in Charlottetown. You can find an interactive schedule at thebus.ca. From that site you can also get to the schedules for the other bus routes in Charlottetown.
You can take a tour of Charlottetown by bus. Trius Tours offers several tours of the Charlottetown area. Abegweit sightseeing tours offers tours of Charlottetown, the North shore, and the South shore. They also offer to pick you up at your hotel. Prince Edward Tours also offers several tours, including Japanese interpretation and a beach shuttle. I believe these are the people with the double decker pink buses shown above but I did not see the pink bus on the website.
If cycling is your thing, GoWheelin has several 1-day excursions that include a bike rental. They also offer a shuttle service for those who want to travel tip-to-tip on the Confederation Trail. If you prefer to just rent a bike and make your own itinerary, MacQueens offers bicycle rentals and various shuttle transportation services.
Whether walking, cycling, busing or drivings, there is plenty to see in Prince Edward Island.