Only time we were able to catch a glimpse of the Tasmania devils, koala bears but miss the kangaroo as they were being moved. Still worth to visit the reserve & prepared for 1.5hs bus ride (one-way). Have the bus driver drop off at the terminal gate to catch street car #109 to Wellington Downtown on the way back as the streets car within the central business district is free. Or you can stroll along the beach in Port Melbourne.
No need to join any excursions if you just want to explore the city as easy to catch a street car from the terminal (buy a transit day pass for $14)
Read marvick5520's full Celebrity Solstice cruise review