My 14 month old son is quite taken with his rucksack. He carries it round the house with him at points. He hasn't really tested it properly yet as he is generally quite content to hold hands, but knowing that even if (when) he tries to run off I have a way to stop him running into roads etc is reassuring.
The pocket isn't massive, but how much do you want your toddler carrying? If it can have a toy or his drink / snack then I am quite happy, and this can. I don't expect him to carry the contents of the changing bag.