Miracle Noodles boast that they are calorie free noodles. They are made from the fibre from the root of a plant called konjac. Konjac is popular in parts of Asia including India, Korea, China and Japan. It's used more for its texture than it's flavour (as it essentially has none). So it works well as a flour or jelly. The noodles normally formed are called shirataki which has minimal calories (about 20 for a 4oz serving).
The Miracle Noodles are made strictly from the fibre of the konjac plant called glucomannan. Glucomannan is actually quite common in supplements for weight loss and type 2 diabetes.
I was lucky enough to find a friend who has the miracle noodles and cooked me up a batch. I can tell you that the smell coming out of the bag was less than pleasent and my friend explained that if you rinsed and and parboiled the noodles, it went away (which it did).
I had pretty low expectations about the noodles and was not expecting anything close to pasta and as it turns out I was right. The noodles taste nothing like regular pasta noodles, but covered in enough sauce they were tolerable.
So I'd say if you're looking for a pasta alternative, this may be an option, but here are a few things to consider.
1) Because these noodles are strictly fibre, they cannot be counted as a grain product and in no way have the same nutritional value as grain products like rice, pasta or oats.
2) Health Canada warns that foods containing glucomannan need to be taken with 8 oz of water as chocking is a concern. Glucomannan doesn't dissolve like regular fibres do from saliva so physical chewing is the only way to do it. Because of this, the noodles could potentially get caught if swallowed whole and won't break down. (There are recorded incidences in the states of people choking to death on jellies made from konjac (mostly kids and elderly that might have swallowing problems to begin with).
Final verdict: not very tasty and not nutritious, but if you are trying to watch your intake you might want to give them a try. Just don't think you are getting any real nutritional value for your buck. Also, be sure to chew really well before you swallow.