[x-posted from dpreview forums]
Make it a bundle with the K-r, as with the old SLRs with a fast 50. That will send the signal "Pentax is the brand to get if you want compact and great primes".
And with high ISO being what it is with the new crop of APS-C dSLRs, a 35 f2.4 gives you much more low light capabilities than we ever had with a fast 50 + film.
What we lose is the possibility to get a really narrow DOF. But imho the difference between the competition's f1.8 or Pentax f2.4 is not a very big deal. The ultimate street lens for Pentax APS-C would imo be a cheap, small, 35mm f1.4 prime, but that is not very likely to happen, now is it?
If it has IQ as other Pentax lenses it will make one or two new owners think one more time before getting the kit lens.
And that is where we should see the place of the new DA35f2.4. Not as a rival of more expensive primes DA35macro or FA31, but an alternative to the 18-55mm kit, which @ 35mm has a max aperture of f4.5.
To me f2.4 is a big improvement over f4.5 at that FL. And it will show in the images the new buyers will get from their system.