Thank you for all your replies. It's interesting to see how mixed the replies are -- some women love them, some hate them. Not a lot of in-between.
I have to say that I am not opposed to Spanx in principle. The ones I tried on were ridiculously tight, but perhaps I should try again, because some of you find them very comfortable. I have a few outfits which might benefit from shapewear, but I'm only willing to make a small sacrifice when it comes to comfort!