I would say greyhounds are no worse or no better then any other breed of dog. They are just like any dog in some respects. We got lucky as she likes everyone, is a sweet and loving girl and gets along with most dogs! Even my sister's hyper Vizsla! First time they met, he was a little to close and excited for her taste so she gave him a few barks and that was it! Now they are good friends, even sharing each other's beds.
I have found the only type of dog Milly doesn't care for are very loud/in your face dog. She will either walk away or bark at them. Note: greys are generally non barking! They also shed very little, have little to no dander and don't have a doggie smell!
If there are any more questions, just ask! They are awesome dogs!

Here is a full shot of Milly. She is 24" at the shoulder and weighs 55 lbs.