While I think that the Centre Island experience could do with a facelift, it is still very popular and most definitely a popular destination.In my opinion - scale/size of the park, range of the facilities (gardens, open grassland, forest, playgrounds, sports facilities etc) and location - something that Toronto lacks in the downtown at present. Something that both tourists and locals will travel to especially.
Toronto Islands is too far from downtown, the new Portlands park may be considered a destination park.