Ilford HP5 does a great job in most lighting conditions when shot at 400ISO, however if you find yourself caught out on a particularly light or dark day, HP5 has a wide exposure latitude and I've had great luck pushing and pulling it. In general it yields middle of the road tones with nice contrast. It is interesting to try different developers with various films though, as they will each yield a slightly different result, especially when it comes to the contrast of your film.
If you compare the Ilford Delta 400 to the HP5 400, and look at it very closely, you will notice they have a different grain structure. The Delta has a T grain structure whereas the HP5 has a cubic grain structure. This means the actual physical shape of the individual grain in the film is different, giving each film a distinguishable look. The Delta film with its T grain shapes tends to look more fine grained, and you don't notice the grain as much. The cubic shape of the HP5 grain is more pronounced, giving it more of a grainy look. I personally like that effect of the HP5 and prefer a bit more pronounced grain in my photos.
Here are a few photos from my family farm in Manitoba this summer shot on HP5 120 with Nicole's RolleiCord.