Whether or not it's a "flagship" is totally a matter of semantics and it's pretty much meaningless to argue about it. HTC says it's their flagship, it's their flagship. End of story. Refusing to allow it the label because it doesn't hit a few checkboxes on your personal list accomplishes nothing and helps no one.
Frankly, the design is incredible. I checked one out at the AT&T store before I bought my girlfriend's 920, and it just felt great in hand. The size, shape, and the material were just perfect. Loved the color. Screen looked gorgeous. I still went with the Lumia 920 due to double the internal memory, wireless charging, super-sensitive screen, Nokia Drive, and no "Beats Audio" nonsense. Girlfriend went with the Lumia due to the increased memory and for Nokia Music (she's a big music streamer).
If HTC doesn't give up and iterates with some things to challenge the Lumia, I wouldn't hesitate to pick one up for my next phone.