I love this medium sized pet carrier!  It's easy to carry and even better for rolling. Because of its vertical design, it puts less strain on my arm and back when carrying. Rolls smoothly. I can seatbelt it into the car.
My cat is not thrilled with it, but she doesn't panic or try to claw her way out. She can see out 3 sides. 
It meets the airline space limits for Delta and American Airlines, but not for United. If you want to take your pet in cabin, carefully check your airlines standards