I got this case for my 3 and half year old daughter for a recent family holiday. She is absoultely thrilled with it :-).
It held all her clothes for the week (just about, but we fit them in there!) and she was able to wheel it herself which was great for me with a small baby in one hand and luggage, passports etc in the other! It's small enough for carry-on luggage but we checked it and it was fine. It will get lots more use on weekend trips to grandparents and the like.
The only negative i have is that it mightn't be the most durable, although it was durable enough to check on for a flight which trunki's aren't. And i think it will last no problems until she grows out of it.