As others have said, yes these costumes are big. To give you an idea of how big, we have two boys;
4 yr old at 106cm (87cm to shoulder)
7 yr old at 121cm (100cm to shoulder)
We bought this 3-4 yr old costume for our 4yr old. However, its massive on him, fitting perfectly our 7yr old instead! We looked up on another website which gave actual sizing figures (so we did try), and it said that the toddler costume caters for child heights (to shoulder) of 84cm max.
The sizing is obviously screwed up.
I think the outfit overall however is good. The mask, cape and body suite I have no qualms with. The major let down is the belt which looks like a bit of plastic with a pair of tights tied to either end. I've looked for a better belt (and one which can perhaps even hold the bat symbol boomerangs supplied) but can't.
Looks like we'll have to make one!
As the sizing is so outrageous, we're now asking for a replacement at the smaller size.