This Dell Latitude E6540 worked flawlessly out of the box.  Over-all, it's very fast.  On first boot-up, it did not go through a Windows setup.  Instead it booted up straight to the Windows desktop.  I checked over everything to make sure all was working correctly.  The only issue I had was that the head plate on the DVD drive was falling off on one end of the drive.  So, I had to use some glue to keep it in place.  I was a bit disappointed that the keyboard didn't have the back-lit feature.  In the illustration on the Amazon web side, it showed the back-lit key.  I know that key since I did have another Dell Latitude E6540 which I setup for someone else.  It did have the back-lit keyboard.  Over-all, the performance is great.  I have not checked how long the laptop will run on battery power.