I have used Lightroom 4 before recently got the 5, I was already familiar with how to use the software. Let me say this: This "digital darkroom" spoils anyone who has never worked in an actual darkroom. Lightroom 5 makes it easy to make adjustments to your images, yes, but it also takes away the headache of importing and archiving with its import feature.
For someone diving into the software head first, the learning curve is moderate, but for the most part, the user interface flows well. As a travel junkie, one of the best features of Lightroom is its intuitive map module, with which you can plot the location of any photo in your library.
I have not used any of Lightroom’s competitors, but I know that what it does, it does well. 5 supports the D600 tethered shooting, which I’ve used for some macro shots. It would be nice for the tethered shooting interface to be a little more complex(such as allowing delayed release), but I guess that’s what the dials on the camera are for.