I recently shot some APX 25, 100 and 400. I processed in dilute Xtol.(posted 9758 days ago)APX400 impressed me as being a very decent film; sharp, finer grain than Tri-X but not not as good as TMax400 in either department, and not as good as HP5+ in terms of grain.
APX100 is a nice medium speed film, probably better than Plus-X in grain, sharpness and tonality, but not close to TMax100.
APX25, ahh, talk about the classic fine-grain look, albeit with a pronounced shoulder that flattens highlight contrast. I usually prefer a straight-line look but APX25 can be pretty cool when used on skin in hard light - have a look at http://www.source.net/dana/photo.html for 'Velvet', shot on APX25 135 for an example.
Dana K6JQ Dana@Source.Net