I like that the box is small and she can carry it around. What I don't like is the top is difficult to take off. I think a flip top or an open red basket would work better.
Originally the boxes came with 4 items, but I have gathered a few more to put in her red box. She has had a great time pulling items in and out of of the box. So far, the ball and the car have been her favorite red items.
When I introduced her red box, I put it on her mat and let her explore. After 2 days, I presented the box on the floor with three items. I picked up an item and said, "This is a red ____." I repeated it two more times.. She explored the three items and I said, "Wee One, can you please give me the red ____?" If she didn't give me the correct item I would hold up the item I had asked for and said, "This is the red ___." The whole time it was kept light and fun with no pressure to be right.