I have been using nexus 5 for about three weeks and as much as I love the smoothness of this phone, I cant wait to have some money to exchange it with a samsung phone, at least a samsung s4.

I was using a samsung s3 before that phone has a broken power button (keep booting over time by itself). Below is  a list of what i feel the pros and cons of the nexus 5 over samsung s3:
Pros:
really smooth,
superbly smooth,
battery can last me a whole day with sot of more than 4 hours.

Cons:
no sd card ( seriously, a bummer),
camera is really pathethic ( ois makes all my pictures taken qith it blurry, color reproduction is so much worst compared to s3 and the s3 was so much consistent in taking pictures),
no smart stay (cant stand that i have to keep touching the screen everytime i read something using it),
no notification toggle like the touchwhiz( i know i can find apps that let me do it but i like the touchwhiz one a lot, you can scroll to see most of your settings toggle or you can click a button just beside the setting button and see all your settings, really miss this feature),
The nav soft keys ( really hate it, fast switching cant exchange with the fact that it is taking some space of the screen. When you are using different locker, this pathethic bar cannot be hidden)
love the app drawer animation of touchwhiz compared to fly in app drawer of the normal google launcher)

My wife is using a note 3 and everyday i feel jelous of her note 3 features. Rarely lag and most of the time is as fast as my nexus 5.

Btw mine is a uk set wrapped by an ultra fit copper gold spigen case.