Shifting into 1st and Reverse should NOT be hard
I had an '05 CTS V, unfortunately had to sell it and I had the same problems. Once I had to push the car out of a parking space because I couldn't get it into reverse. I took it to the Caddy dealership and the bushings where the shifter meet the transmission had worn out, made perfect sense once I found out, but I thought it was a serious problem. This will happen even quicker if you have replaced your stock shifter with a short throw one, such as B&M. If you are going to replace your shifter make sure you purchase the B&M bushings to have them installed as well. Hope this helps you guys out.
-Miss my V ;-(