Our son (almost 5) has been asking santa for these for a couple of months now. Given the exhorbitant price tag ($40) we held off thinking that he would forget about them. It's now the only thing he's asking santa for so we figured we'd better get him a pair ($28 at TRU with a 20% coupon which we didn't think was so bad). Given all the negative reviews, mom thought she'd better check them out first.
When taken out of the box, the only assembly required is for both ends of the wing; there is a plastic rod that inserts into the joint that forms the top part of the wingspan. It seems sturdy enough but whether it will hold up to repeated openings/closing, I don't know. You put the backpack on and it seems pretty secure with a strap around the waist and a strap coming down each shoulder to connect. On each shoulder strap there's a cord; to open the wings you pull down on the cords at the same time and hey presto, they snap open to their full 5-ft wingspan. I have to say, that it's pretty impressive and I know that my budding batman is just going to think that he is the business with these things on! To retract the wings again, you pull on the cords until they are closed; for me it took about 4 pulls until they were completely closed. Whether my guy will have the patience to do this, who knows! I suspect they'll maybe do one or two pulls until it's 'good enough'; problem is they'll probably get broken from them running into something that's too narrow when they thing they've pulled the things all the way in. So, the mechanism would have been better designed with a single pull to close.
I think my son will have a blast with these on christmas day but I don't expect them to last too long. I didn't mind paying $28 for these, but think they're probably worth around $20. I made sure that I bought them from somewhere with a liberal return policy as I fully expect to be returning them broken at some point after the holidays.