Very comfortable and allows you to carry an extra magazine.
I wear my Ruger LCP everyday and I have to keep my shirt tucked in at all times. This is by far, the most comfortable and easiest tuckable holster I've ever worn for appendix carry. Even on the hottest of days. I love it so much, I'm going to get one for my S&W Shield 9. My only addition to the design, would be a thumb retention system.