Optical viewfinders (seen on some similar 'interchangeable-lens' cameras) are pointless - you wouldn't be able to see what the sensor is seeing! The lack of an
optical viewfinder (as much as I would hate not having one) is irrelevant in many ways - it's a mirrorless camera, so it would have to be an electronic viewfinder. If it had one, I'd be seriously looking to buy it..... as a 'walkaroiund' camera.
And it's not quite the only thing making it smaller than a DSLR..... That 40mm-f/2.8 pancake lens (angle of view of a 60mm) is so 'thin' that you hardly notice you've got one - and the camera with that lens is still only about 2.5 inches 'thick' (a tad over 6cm).... about 1/4th of an inch more than with no lens. It's a chunky camera, no doubt about it - jacket pocket rather than my jeans...... but it has some very nice specs.
More stuff here.
I hated the thing when I first saw it - but I'm warming to it. It has good qualities - price, sensor (pretty much identical to the K5), top of the range video capabilities, HDR and more. And it certainly looks different! The NEX5 has lower resolution similarly priced and is truly trying to be a compact - but as soon as you put any lens on it it's less compact than the K01. So the choice is - chunky camera, thin lens (K01)........ or elegant and lightweight compact - which ceases to be that as soon as a lens goes on it (NEX).