I bought these based on my personal trainer's recommendation.  I was using my running shoes (I know, right?!) for squats and weight training.  I definitely noticed a HUGE difference right away.  These keep me anchored and help with my form.
The only reason I gave them 4 stars is that I used them for my HIIT class and they rubbed my ankle a little.  I think socks a little higher would help, but I like the no shows.  I did notice,  however,  they are good for plyometrics.