Whilst the DK2 is a huge leap forward in screen quality along with positional tracking, and latency improvements...the resolution increase does indeed leave a lot to be desired.
I can do without positional tracking, and the latency improvements for now...and so I see no reason to change my DK1 for a DK2. I was honestly hoping the resolution would be better than it actually is. (But that said - it is all still a great experience!)
IMO it's a step up from a DK1 but not massive. I think the issue is the pentile screen and the fact that there are less red/blue subpixels than RGB which the DK1 had. A lot of people that tried the 1080p RGB HD prototype said it looked higher resolution than the DK2 does, it had other issues though such as ghosting that were resolved in the DK2.
I know the crescent bay prototype was OLED but not the subpixel arrangement, hoping they've got back to RGB layout or even stacked subpixels.
The new lenses in the crescent bay prototype apparently increase perceived resolution, they didn't confirm the screen res but many people thought it was higher than the Gear VR which uses a 1440p screen. Reading between the lines of what was said by OVR I think it was a 1440p screen with the new lenses making it look better.
IMO the resolution aside things like the 75hz low persistence display make a bigger leap over the DK1. Much more comfortable to use than the DK1.