I have actually had proper lucid dreaming a few times now. The first time I ended up with sleep paralysis which was quite scary. I now understand where most of the “alien abducted me when I woke up” or “I saw a ghost when I was woken up in bed” etc stories come from. Your mind can be very scary when its half dreaming and half awake.
But I have had other lucid dreams where I could do whatever I wanted. I flew about, I had matrix style fight with bad guys…..great stuff! The sooner a machine that induces lucid dreaming is created the better, the ultimate interactive entertainment!
So in summary, lucid dreaming good, sleep paralysis bad. ;)