I got a GR X BC mix about 6 weeks ago. He is the most placid, cute, and intelligent dog I have ever owned. He is very loyal but at the same time independent. He was a breeze to housebreak, learnt his name within two days and can come, sit, lay down and shake hands.
For a puppy he is quiet well behaved (despite a few holes out the back, but I've had worse before). I think this comes down to his relaxed temperament and the fact that we also have a whippet, who is the most lazy dog I have ever had the pleasure of meeting!
All in all, my little Jet (that's his name) is a beautiful dog. But I guess I got really lucky with him. Not all mixes are predictable. Just make sure you meets the pups parents, spend some time with the pup before you get it and make sure the breeders have had the dog vet checked, vaccinated and microchipped.