I have no doubt it is. All high-end phones are impressive in their own ways. However over the years I've gotten less patient with phones, so I don't bother rooting/flashing stuff to it, I just want it to work out of the box and provide an excellent user experience in every facet of the phone. If I have to root the phone or put a custom UI on it, then the phone has already failed.
The HTC One is the phone that comes closest to being the best in every aspect in my opinion. Design, build, speakers, screen, UI, speed etc are all best-in-class. I like the Sense 6 UI more than stock Android KitKat and I've yet to use a phone that's faster in operation. Even the 3gb Ram Xperia Z2 I felt had noticeable lag and stutter around the UI.
The only slight miss-step on the HTC would be the camera, but even then it would only be in certain situations, like big landscape shots where you need large amounts of detail.
To be honest, the only thing that has me interested in the G3 is the screen. I don't like the look/design of the device, speaker I assume would be some stock speaker other OEM's use, UI may be improved and hopefully scaled back from what the G2 was, I really hope the phone performs faster than the G2 as well. But yeah, if the G3 didn't have the 1440p screen, I doubt I'd check it out.
The only phones in the future that really interest me is the Nexus 6, if that's going to happen, and the HTC One M9 next year.