These are super cute! I bought them in the 2T size for my 2yr old son. The shirts fit great and the pants fit alright. I posted a more in-depth review on the Captain America style, but basically, the pants fit in length and waist, but they are sort of slippery and easy to pull off on a toddler who spends a lot of time crawling around being silly. Not a huge problem, just have to tug them up a lot. The hooded masks are really cute and he has a blast wearing them, even if he is not quite sure who Capt. America or Iron Man are yet, haha :)
The sizes seem to run a little big (long and wide) but the quality is nice. I also ordered the previous size down and that seems to fit my son better (he can wear 2T and 3T and the 3T is larger and does not fit around his waist well, maybe next year. The quality is good, the pants are comfy. I like this especially for the price.
My son is 3 1/2 so I ordered 4t and he loves this outfit! It's like a costume for his since the hood is a mask. The face mask is mesh so not too heavy on his face when he wears it and the pants are a soft material.