strolling through the forum will give you the answers you seek, however I will help with some of your concerns.
as to the build quality of the device, smoke over this thread:
HTC one build quality
in a nutshell, the black has been shown to scratch easily and show fingerprints more so than the white/silver
as for your BT concerns, smoke over this thread:
HTC One Compatibility with in-car Audio/Bluetooth/Hands Free
BT quality is top notch on this device, but YMMV with your particular car and its compatibility with the bt stack that is employed on the htc one.
for headset quality, this is also good. I use LG Tone BT headphones and they are just wonderful. there are some wired buds with some flavors of this device in the box but you will most likely want to go aftermarket. again there is a thread on accessories for the one you should also smoke over.
as for your GPS concerns:
Antenna (includes GPS), reception discussion
all you want to know about the phone and its reception. in theory you only need 4 sats to geo locate accurately and this phone overall has good scores in that area.
you may want to also smoke over reviews from users here:
Real world reviews & comments from actual users
in the end though, its up to you to decide if you should get this device or not. no one can make that decision for you. your environment and requirements are unique to you. stop by the carrier of your choice and take it for a test drive.
Originally Posted by ITemplate