The only bad thing about this onesie is that it is really baggy. The sides will be flopping and so does the crotch area. It doesnt give you a lean look at all as this one reviewer has said.
As far as getting warm, it does its job.
I am 56, and the onesie is really short. It doesnt go down to my ankle. It is a capri pants length.  In addition, if you raised your hands up, the pants will go up to your knee.