It it's anything like the Voigtlander 17.5 it will be a very different look, even stopped down to the same 1.2 aperture or F1.4. From samples in the native image thread, it will be a little busier and overall a lot softer.Very cool comparison. The Fuji's rendering definitely looks busier in the backgrounds. That Oly 25 is a helluva lens.
Edit: Now compare it with the Voigtlander 25mm!