Using this for almost 2 years now and it is still as good as new.
Comes with stock android and no user interface. It came uploaded with Android KITKAT 4.0.4 and has upgraded to Android Marsh-mellow 6.0.1 till date.
2GB of RAM has made gaming & multimedia on this phone a lifetime experience.
Camera is good and has panoramic view as well.
It has a 4.95 inch screen and best screen to body ratio making it too hand and catchy.
Leather touch back adds beauty to this beast of phones.
Battery is non removable and lasts almost a day on wifi and decent mixed usage.
Pure stock Android version makes it more user friendly than any of the phones with additional user interface created to add visual sophistication.
Coming to cons, it has only one sim card slot making requirement of an additional phone , if you are a heavy phone user, because you cant rely rely on smartphones for heavy voice usage specially while on the go.
Storage is 16 gb, out of which only 12.55 gb is available for usage.
No additional memory card slot is provided , however the same can be added using OTG devices at almost the same price and in a more professional manner. Nexus 5 supports OTG devices to add additional storage space.
I love my Nexus and am a proud owner.
(experienced it for more than 2 years now and it is as smooth as butter till date)