I like the concept: ice cubes that conveniently fit through the small hole at the top of a water bottle. Not only that, but a whole bunch of them, ready whenevery you need 'em.
Using the tray is simple. You make sure the base is secured to the tubes (or else the water'll leak) and then fill them 3/4 with water. You freeze them, then run the tubes under warm water, remove the base and turn upside down, and voila, you have ice tubes.
Unfortunately, this works best for water and juices, and nothing else. I originally bought this because I was looking for a way to freeze homemade baby food. I'd gone on a random search for silicone ice cube trays but couldn't find any. Instead there were the cheapie plastic ones and this. The idea seemed the same as if I were to use the silicone trays so I purchased it (well, I almost didn't to allow myself time to think it over, but my son had gotten ahold of it and gave me the look of utmost shock when I tried to take it away).
I've used it both for pureed foods and water. I have to say, it does great at making ice, but I had a few problems using it for the food. Since the food sticks in the tubes I have to push them out, but the cross sections in the center tube make that fairly difficult. Plus, for as much as the tubes freeze, they take up a lot of room. The biggest problem I have with freezing baby food, though, is the cleaning. Boy are these hard to clean without a special brush (which I don't have).
The idea is great, just not the best for baby food. I will continue using this product for my water and juices, but will get silicone trays for baby food.