A 50mm prime lens is the classic "normal" lens for DSLRs. It's a very similar perspective to what we're used to seeing with our eyes in real life. It's sometimes known as the "nifty fifty" because it can be a go-to lens for all sorts of things. They're often small and light, and even surprisingly inexpensive.
With relatively simple lens designs that are tried and tested, they also happen to be some of the sharpest lenses available. That doesn't, of course, mean they're equally as sharp at every aperture, and often they can be a bit soft wide open. That's true of this lens--at f/1.4 there can be a slightly ethereal effect to it. That's not necessarily a bad thing--just a performance quirk that's worth being aware of.
A 50mm lens is also a great first prime to get if you're looking to upgrade from a camera's kit lens and dip your toes into the world of prime lenses. If you're using a DSLR with a cropped sensor, it will turn the 50mm into roughly equivalent to a 75mm lens on a full-frame camera. That's approaching the lower end of the range for a moderate telephoto. The major lens manufacturers produce 50mm f/1.8 lenses that are very sharp and surprisingly affordable. This f/1.4 version is over double the price of it's f/1.8 sibling, but it's still quite affordable considering its quality and versatility.
One of the things I like most about this lens is its versatility. While it might not be the perfect lens for every type of shooting, it can handle a very broad range of shooting conditions well. Whether you're shooting a wedding, a travel destination, a restaurant's food, candid family shots, or street photography, there's a good chance that you can come away with some great shots.
And that holds true in an unusually broad range of lighting conditions. With a maximum aperture of f/1.4 and a moderate focal length, it opens up possibilities for hand-held photography even in very low lighting conditions.
Nikon has two autofocus 50mm f/1.4 lenses in their current range. This one is the "G" version and is the newer of the two. It's designed for newer Nikon cameras and doesn't have an aperture ring--that's all handled in the camera. There is also still available an older "D" version that includes an aperture ring (and will still work on newer Nikon cameras).
Here are some example photos I've shot with this lens to give some idea of how it performs in real-world shooting. If you'd like a closer look, you can click on each image for a full-size version.