I am on the verge of buying a KR, after using a canon 400D for 3years.
The most important feature from K-R that's not mentioned much in this forum is the micro adjustments for focus and it's a pain not to have them when you hear so many stories about FF & BF with some of the 3rd party lenses (sometimes Canon lenses too!) and people ending up getting a "over-serviced" body/lens and have wasted so much time and energy for nothing...... Yes, Canon does not offer it in their cameras that are under 1200USD, and I was prepared to pay for a 7D. But luckily K5 had many great reviews and I started checking on Pentax and I found that Pentax K-R is all I wanted. I am now in the process of selling my canon gears and getting ready for my Pentax!