I have the Pentax 50mm f1.4 and would highly recommend it. I purchased it last November and have used it frequently. As others have said, this lens represents great value for money. I also agree that wide open, it does produce a soft image, though it's still nice to have such a wide aperture available for use. Whether or not it's usable
depends on your standards, I guess.
On a visit to the museum, I kept to apertures of f2.8 and f3.2 most of the time, which worked out very well. But I was also happy with a shot taken at f2.2, even though I used ISO 3200.