The other day I talked about Kollage's Sqaure knitting needles now being made in the United States. They sent me some needles to play with and it was a lot of fun trying them out! The stitches are definitely smooth and even with these needles, and I think they seemed a little easier on my body than regular knitting needles, though I haven't really worked with them enough to know that for sure (I'll let you know when I find out!).
The one thing you need to know about these needles is that they won't give you the same gauge you would get on a same-size round needle, so be aware of that if you're purchasing needles for a particular project. They recommend going a needle size bigger than the yarn or gauge of a pattern suggests, and I found that to work pretty well as well.
If you've used these needles before or give them a try, I'd love to hear what you think!