I love the convenience of these cups. You can blend your shake, put the lid on and go. The downside to these cups, are the lack of measurements on them. It's really annoying to have to use another cup to measure out all of my ingredients to pour into this cup. Design oversight. The other thing that I've noticed is,  on the blender attachment for these cups. If the rubber seal isn't just quite right, it'll leak all over the blender itself. Overall, a good product but could definitely use some tweaking.