Ilford HP5 Plus 400 is a classic, grainy, black and white film. Its characteristics include greater edge contrast and apparent sharpness. The film has a certain raw look that lends itself to an edgier composition. Similar to Kodak's popular Tri-X 400 film, this film is full of subtle imperfections, and it's those imperfections that make this film so wonderful.
Ilford HP5 is extremely flexible and forgiving. Amateurs love it because its flexibility makes it an easy beginner's film. Mess up, and this film will give you an image worthy of print. Professionals prefer its flexibility in order to worry less about their camera's settings and focus on their subject.
The film has a narrow tonal range, but I find its not as narrow as the similar Kodak's Tri-X 400 film. Images with a narrow tonal range tend to have a lot of depth, and as mentioned before, are more contrasty and grainy. These characteristics portray a unique drama that lends itself well to certain genres of photography: rock and roll, sex, drugs, war, documentary, etc. It's a film with a very raw and real look.
If you're looking for beauty, fine art, or grainless photos, you'd best check out Ilford's Delta films. If raw, real and grainy is what you're looking to portray, then grab a roll of Ilford HP5, and enjoy.