Adequate, not great, not terrible
It is named as Ultra-thin, but it does add quite a bulk feel to the phone and I definitely had slimmer cases for other phones I owned. It is noticeably slimmer from the other, regular Olixar case.
Picture shows perfectly clear and slick case, but inside is covered with micro-dimples which diffuse light and make more white-gray smoke effect, which I do not appreciate.
On the plus side, it is one of barely few cases actually available and makes glass phone not slippery.