I have both a 2013 Honda Accord LX and a Nexus 5.
Every bluetooth feature works flawlessly with the phone!
The Pandora app integrates seamlessly for me. If/when I leave the Pandora option on in the car, as soon as the bluetooth connection between my phone and the car is made, Pandora starts right up on the Nexus 5.
My like/dislike buttons work too.
That being said, I do see comments about it not working for some people with their Android devices. I am curious if that's due to my Accord having different software? (I only picked up the car 3 weeks ago.)
Charging the phone via the USB port works fine, but I still prefer using a 12v charger. Two main reasons for this:
1) Whenever I plug my phone to the USB port with a micro usb cable, it puts the Nexus 5 into a file transfer protocol that doesn't turn off until you restart the phone.
2) Charging with the USB port charges the phone in USB mode, as opposed to AC mode. There are plenty of forums and articles that go into detail the differences between the charging types, but to give you a quick explanation: USB mode = SLOW, AC mode = FAST
Voice commands work pretty well, but this is more of a Honda thing than a Nexus thing.
Call history gives a full call history. And the automatic Text message notification/reading works on the phone as well.
All in all, I'd say go for the Nexus 5, you won't be disappointed.