Although I've heard that rhythm beads are supposed to help the horse, I always thought they were just for the rider... They may help some horses, but not all of them. Some horses might not like them just like some people might not, but I think if you're trying to learn rhythm, it could help. How the horse reacts to them is up to the horse himself. Some might like the sound, some might not care, some might need time to get used to it and some might think it's an army of flies waging war on them.
Although really pretty, I don't think I would buy a halter or bridle like that because
A.) it looks like it would get tangled easily and
B.) I don't think my horses would like it, although they might get used to it, I don't think they will. They're both drama queens.
Although I do like the looks of the ones that go around their neck, I probably wouldn't buy those either, unless I was going to use them in a parade or something.
So, if you're looking for something that purely helps with rhythm, a little bell might work, just something that makes a bit of noise but not too much. You can tie it to your tack. If you're looking to buy something that's pretty, too, I would stick with the neck pieces unless you feel that your horse would be okay with that kind of bridle/ could get used to it. It depends on your horse.