Having the phone for a week now, figured I'd post some extended impressions.
A week after getting my GS3, I didn't have that "awesome new phone!" feel, hardware wise. Software side was a different story, as it was my first introduction to Android. Poppped it in a case a few days after getting my S3, and every time I took it out, I never had that "Wow, this thing is beautiful!" feel.
Not so w/ my HTC One. I've been in the office all week, and had some business partners in yesterday. Most of them had GS3's, and were completely blown away at how crisp the HTC One looks sitting next to the GS3. One guy summed it up pretty well "My GS3 is like plastic Voltron. HTC One is the metal, superior model". Heck, I still pick it up just to hold it. I haven't held a phone this comfortably since the iPhone 3G.
Audio is also incredible. Even through headphones, and as much as I hate to admit it due to the BS marketing, but it does seem like there is something to be said about the beats audio. Everything sounds way better than it ever did listening to my music through my GS3.
Camera, the area that I really thought I would be the most disappointed with, is actually surprising me. Sure, zooming in on shots can get a bit messy, but normal point and shoot shots look great.
Overall, I am extremely pleased w/ my purchase. I kept telling myself over the past few weeks "The want for this phone will pass......." but twice I was stopping at stores just to mess around w/ one. Hasn't happened since the iPhone 3G for me.