I bought this product as I have weak joints and I wanted to improve my core strength. My physio recommended getting a balance board, and this one seemed very reasonably priced.
Taking it out of the box, it looked like a cross between a UFO, an old-fashioned LP and some kind of liquorice confection. Round and black, with bobbles on, and a red circle in the middle. It's made of a special non-slip tough plastic, and the bobbles also help to prevent slipping off. It is sturdier than you might think, and my husband (who is 6 foot, and of average build), can stand on it without any threat to its structure.
When I first stepped on it, it was quite scary, I couldn't stay on there and I kept stumbling off. (As you don't fall very far it's not really that scary, but it was more the lack of control that worried me). This made me think that I had no core strength at all! But I think it just takes practice to know what kind of movements make it balance, and as I practised a bit that day I got better at it. The muscles that you have to use to stay balanced are the ones that you use for core strength, and obviously the more that you use them the more toned they're going to get.
Incidentally, the first time my 6 year-old used it, she could balance perfectly and do all of the exercises included in the instructions. She couldn't understand what all my wobbling was about! It just shows you, I suppose, how much core strength we have naturally when we're children, and how, without the right exercise we tend to lose that over the years. I have to say though, now that I've been using it for a bit I can do most of the tricks that she can do!
I can see some improvements in my own core strength and the balance board also teaches me how I should be standing. (Sometimes it's easy to lose sight of this). I don't use it as often as I should though, so the improvements are probably not as great as they would be if I used it every day.
I would definitely recommend this as a fun way to improve your strength. You can do it while you're watching TV, and I like to stand on it when I'm on the phone. You can do some fun things on it, like spinning, when you're feeling a bit more confident. And you can pretend that you're on a skateboard! You can also sit on it - as you have to adopt a good sitting position to stop it from wobbling, it's good for your posture. When my little one starts to do jumps on it I do start to worry a bit for it's safety, but it seems to be quite hardy and ruggedly built.
I would recommend this as a fun and easy way to gain core strength. It's not imposing on your time or on your space, as it's so small and can be easily tucked away. Although as it's a good form of entertainment for young (or older) guests too, you might not want to put it away, ever!