For some the screen may be too big lol. The overall build quality may not bother most but it did slightly bother me at first (I have a bit of OCD) sometimes the power/unlock button may be difficult to press given the size of the phone. Some volume rockers are a little too loose however that issue seems to have been fixed by HTC's manufacturing already so getting one now shouldn't be an issue. The camera button does take some getting used to, however, once you do it works nicely (the fake chrome does start to chip off of the camera button for some weird reason... I've had two HD7's and it happened to both not a big issue as the underlying paint is practically the same color lol) um... What else... The battery cover kinda loosens after a while but you stop noticing it, at least I did, and given that I have a certain degree of OCD it shouldn't be a problem for most. That's it in terms of hardware, software-wise they're all the same across the board (obviously) there is the notorious "pink" issue with the camera; in which when taking a picture with flash, whites look a tad bit pink however I heard from people over at XDA that the firmware updates HTC have for the NoDo update fix it so it shouldn't be a problem much longer. That's it. Hopefully I didn't deter you because the pluses with this device far exceed the length of this paragraph.
I have had my hD7 for 2 months and the only issue I have had is on 2-3 occasions after I muted the phone, when I turned the volume back up nothing happened and I had to reboot the phone to clear the issue.