If you decide to do both zoo + return from Fremantle make sure you pick the 11 am option. 2:15 pm is a little late as you're returned @ 4:45 pm, which is too late for the zoo on the day. If you got 1 day extra you can rebook the zoo tour. Otherwise you will have to let go if you're on tight schedule as mine.
Overall, I enjoyed this package- however, if you are going to go to the zoo and do the cruise on the same day it is a pretty tight itinerary, you can't get off and look around at Fremantle if you want to spend any time at the zoo. Other than that the staff were very helpful and the zoo is great. My only other criticism was that I'm not sure it was clear beforehand that you had to be able to print your voucher. i was staying at a college that didn't have printing capacity so I had to frantically find a copy store that opened up sufficiently early to print the voucher before my cruise. I think this could be made more obvious in the booking process (I suppose I could have missed it?)