Note: this is coming from someone not up to date on the cutting edge of digital cameras.. And all I have to compare it to, from an experience standpoint, is a year or two of occasional use of a Panasonic GF-1 and 20mm lens (both of which I'm still impressed with!).
I used the Pentax briefly, that a friend rented. It had a 43mm limited lens on it.
It felt chunky to grip relative to other cameras, but not too funky.
The whole thing felt very solid, but not too heavy.
Autofocus was similar to the GF-1 from what I could tell. Pretty nice.
Manual focus was really easy with the 43mm, even without the peaking effect. Sweet LCD.
Image quality with the body-lens was way better than I'd ever need.
In short, I was impressed with the lens and photos and ease of use. The body does what it needs to do. It didn't make me want to add stuff to my other cameras to make them chunky, but it wasn't a big deal either. Leica M bodies feel chunky to me when they have a half-case. My GF-1 is still chugging along for what I use it for, but if it goes kaput, I could see it as a replacement.
Around the same time I used the friends Fuji xpro-1. I can't or don't rationalize/reason out my camera preference like some, but I can say I much preferred using the Pentax with 43mm lens.