I consider the 28f3.5 one of the best black/white lenses you can find. It has a incredible tonal range, without blowing highlights. It is a bit slow for some stuff, but when it works, it is stunning.
The 25f4 - particularly in the P-mount version is good, but I run it against lenses like the ZM Biogon 25f2.8 which is truly in a class of its own. It is not that the 25f4 is bad, far from it - for the money it is outstanding, but the ZM 25 is about as good as you can get. Only real competition to this lens is the brand new Elmar 24mm f3.8 Asph from Leica. I did shoot for a day and a 1/2 with this one in Louisville, KY during the LHSA meet. Sharp and virtually unchanged image quality from wide-open to fully stopped down! Much more money though!
I haven't tried the 24f1.4 ASPH from Leica, but if it is anything like the 21f1.4 it is stunning - BUT at $7000 I think I have to accept that a two stop speed increase from the 21f2.8 Biogon or 3 stops from the VC 25 is not worth it. For that kind of money you can hire a guy with a tripod!!!!