I got this for my 4 yr old. He LOVES it! I had a very difficult time figuring out what size to get him but after some research I go the small and it fit perfectly. My son is 40.5 inches tall and 37 lbs, an average 4 year old and I'm glad I did some research because the manufacturers site suggested the medium which would have been WAY too big.
It arrived a month before Halloween and he wore it for a few days when it first showed up, I got the jet pack and gun for him too so he really enjoyed it. He's worn it on and off since then and just LOVES it!
The mask is definately flemsy and when it arrived, the suffocation warning print on the plastic bag the mask came in became imprinted onto the mask front, so that sucked but my son doesn't seem to mind at all.
The costume did get a minor rip on the back where it velcros together but very minor.
I'm just glad he enjoys it sooo much. I really suggest getting the jet pack and gun along with this costume. There's a picture of him above in all of it on Halloween.