We had 2 but somehow mysteriously lost one (playground mishap, I suspect). I bought 3 more, bringing us up to 4. 2 are pretty much loaded in the fridge at all times ;) the easiest to clean, fill and use! Must buy for littles!
We have both sizes but I actually prefer the small 3.5oz size for most things. I take the insert out for things like a smoothie or something thick and add it back in for keifer, yogurt, applesauce. These really help prevent messes if he is feeling like he wants to splash around in his food or dip his hands in it. He can feed himself without the mess. They are super easy to clean.