To me, after I take a cold shower I feel like my mind is clearer and that I can focus a lot better. It kind of feels like how Neo in the Matrix learns how to see through the matrix, with random green numbers flying through his field of vision. Of course I don’t literally see those things, but it feels as great.
Also, as I said in the article, my willpower grew in terms of withstanding unpleasurable experiences. Plus, I don’t feel cold outside as easily anymore.
I don’t think there are any disadvantages. After all, it’s just cold water.
I’d love to hear if you had similar experiences (or not).