The power transformer used in the adapter makes a noticeable high pitched whine, if you have decent hearing. It can be quite maddening at first, but after a while you get a little used to it. For the moment, I just keep the adapter inside a desk drawer when using my laptop at home. Outside of the house, I'll keep it in my backpack or in a jacket while running, and check up on it to make sure it doesn't get too hot.
I had another power adapter that burned out over the winter, and in comparison this one runs much cooler, and is sturdier.
Overall, for people over 30, the whine should not be audible, so it's a pretty decent product.