[pjm1]

The 35/2.4 hardly distorts at all. And the little that exists is very easy to correct.

I was going to say more or less the same thing, but suddenly lacked the confidence of my convictions! I find the 35mm is great for shots including closeups where you want more than just the face. Don't get me wrong, if you're battling with minimum focus distance when you're trying to get a portrait then something's probably wrong but otherwise I find it great for more contextual shots.

I still use it less than my 50mm and my 50-135mm zoom though...

[abhaskare]

This was an interesting read and I faced the same dilemma - whether to go for 35/2.4 or 50/1.8. I have 18-135 and the 50-300 zooms to complement.
I got both the primes - 35 and 50 and did a comp along with 18-135.
Here are the results:
https://www.flickr.com/photos/j0hnnygaddar/albums/72157663191110545

The file names are tagges dith lens focal length and the f stop used. I decided to only keep the 50/1.8 because
1. The larger aperture 1.8
2. To be used as portrait
3. To get a nice bokeh.
4. The 18-135 is f4.5 at 50 mm, so 1.8 is a very nice gain. So really no substitute.

The reason I did not keep the 30/2.4
1. f2.4 is still not great, would have preferrred 1.8 or so.
2. I can get comparable image from my 18-135
3. Although this lens can be used as a walk around lens, I will sure not replace my 18-135 with it.

I also tried the cheaper old Pentax A 50 mm /2.0 which is manual focus but auto aperture (~ $30)..
This is also good but 50/1.8 wins in image quality and sharp auto focus, ease of use.

[normhead]

This was an interesting read and I faced the same dilemma - whether to go for 35/2.4 or 50/1.8. I have 18-135 and the 50-300 zooms to complement.
I got both the primes - 35 and 50 and did a comp along with 18-135.
Here are the results:
https://www.flickr.com/photos/j0hnnygaddar/albums/72157663191110545

The file names are tagges dith lens focal length and the f stop used. I decided to only keep the 50/1.8 because
1. The larger aperture 1.8
2. To be used as portrait
3. To get a nice bokeh.
4. The 18-135 is f4.5 at 50 mm, so 1.8 is a very nice gain. So really no substitute.

The reason I did not keep the 30/2.4
1. f2.4 is still not great, would have preferrred 1.8 or so.
2. I can get comparable image from my 18-135
3. Although this lens can be used as a walk around lens, I will sure not replace my 18-135 with it.

I also tried the cheaper old Pentax A 50 mm /2.0 which is manual focus but auto aperture (~ $30)..
This is also good but 50/1.8 wins in image quality and sharp auto focus, ease of use.

+1^
I'm pretty much the same. I use my FA 50 ƒ1.7 way more than my 35. It's a great lens, it's just hard to find an excuse to put it on the camera. Since I go the 40XS ƒ2.8 as a bonus prize with my K-01, the 35 has barely been on the camera.

[ChristianRock]

Well to each their own. When you have small kids like I do, f2.4 means I can have a faster shutter speed. I can take sharp pictures at 1/10s at 35mm but SR doesn't compensate for movement so if I can have 1/60s with my prime at f2.4 or 1/15s with a zoom at f4.5, guess which one I'll use? That's why I pretty much only use the 35mm when I'm with the family, especially indoors. Plus the K-r/DA35 is such a light combo that I can carry it around all day.
Sometimes if I'm outside on a sunny day I'll use a zoom.

I use my F50 1.7 and my manual fifties for flowers and scenery, so they all get their use. But if I had to have just one lens, it would be the 35 2.4. No question about it.