I put it on the phone and it slipped right in with that reassuring "snap" sound once the lip of the case came to the front of the device. I have a bodyguardz glass shield on my phone and the lip on the case doesn't interfere with it at all! the sides of the gel feel firm and don't warp or bend away so easily which keeps everything smooth and easy to use.
My only problem is the clear piece on the back. It came with scratches and defects on it. Also the cut out for the secondary mic isnt correct. It's off and the mic sits at the bottom right of the cut out. When holding the case, i place my pinky finger underneath the phone near the usb and headphone cut outs and the gel cuts are SHARP! It feels like I will cut my finger but that won't happen. But it is VERY uncomfortable. It hasn't caused any problems but these three issues have only left it from being great.
Case & BodyGuardz Pure Glass
I also ordered these:
SUPCASE All New HTC One M8 Case - Unicorn Beetle Premium Hybrid Protective Case for HTC One 2014 (Frost Clear/Black) &
URBAN ARMOR GEAR Case for HTC One (M8), Slate
Once I get these i will post pics and impressions also.