It is very comfortable to carry as a backpack and it is sturdy. It doesn't topple over when you want to put it down on the floor. The size is also perfect for my growing kitten coz he has a lot of space inside to find a perfect position. And i believe he would be able to use this even if he's already fully grown. The only problem with this is it doesn't have a slot where I can attach the leash from the inside so that I can leave it open.