Before being lucky enough to score my K1, I read/heard many reviews about the DIM screen and up until recently I had bought into the notion that the screen was good, but not as bright. I have had many androids and like most people with an android phone I realized that the adaptive brightness often skewed the perception of how bright the screen really is.
If you feel that your screen isnt as bright -- try turning off adaptive brightness in settings and I think you'll be much happier. Of course this will impact battery life, but c'mon who doesnt charge their phone every night anyways?
On my Samsung phones adaptive brightness was always way too dim. On my keyone It's actually perfect. I never feel It's too dim. This is the first phone I've owned where I can keep it on all the time.