It works (mostly).
I chose a vitamin C filter, which uses ascorbic acid to neutralize chlorine. When my delivery arrived, I excitedly opened the box, which contained an outer plastic tube and several smaller orange tubes (the actual cakes of vitamin C). I'm not especially handy, but installation was a snap. I just unscrewed my showerhead, put a vitamin C tube into the plastic cover, and screwed the whole thing back together.
During my shower, there wasn't the usual chlorine smell I'd become accustomed to, and the very first time I washed my hair in the filtered water it was noticeably softer and less frizzy.
But I'll admit, I was hoping that the filter would be a cure-all and it definitely wasn't. I've since realized that many of my problems were also caused by hard water, and the filter doesn't fix that. But it does exactly what it says it will: it removes chlorine. I will say, I was hoping that the longer I used it, the better the results would be, but that wasn't the case. I found that the improvement I experienced the first time was the best it ever got.
Although I live alone, I do love a long shower, so I've been steadily working my way though my refill cartridges; so far I've used four. It's easy to tell when to change it: the orange cake of vitamin C slowly disintegrates, and I really do notice more tangles and itchy skin when it's running low. I wish I didn't have to change it quite so often because, at $50 for five refills, it does add up. But overall, it's been a great investment, and I'll continue to use it.