The fine grain 400ISO Ilford film, super nice tonal range and grain structure but, dude, you gotta nail your exposures. And you can't just check the back roll a dial and reshoot (well, you can but you won't see anything on the back!) So make sure your meter battery is good or your exposure eye is accurate. Great for architectural or landscape photography. Probs a bit quick for landscape but still good.
Here is what Ilford say about it:
ILFORD DELTA 400 PROFESSIONAL is a high speed, black & white film designed to produce images with extraordinary depth and detail.
Created using our latest Core-shell™ emulsion technology, DELTA 400 produces images with exceptional sharpness and the finest of grain to offer a leading combination of speed vs sharpness along with impressive tonal range.
This highly versatile film delivers outstanding results over a broad exposure range of ISO 200 - ISO 1600 while its ISO 400 rating allows the use of faster shutter speeds yet with the comparable quality of medium speed films.
DELTA 400 can be processed in a wide range of different developers using spiral tanks, deep tanks and automatic processors.