I\'ve been able to retrieve everything but the contacts photo by following the API.
I can get the img url as well as the gd:etag from the xml returned. Below is the Goog
First, you need to make a authorized GET to that url, i.e., in the Authorization header you have to put "OAuth " + AccessToken. Also, I haven't tried but, as Savil has said, with the Access Token as a Query Parameter, you can also achieve the same.
In any case, Google responds you with the bytes of the image, so you cannot display as is. You'll need either save the byte array to a file in your server (I don't think this to be a good solution) or find another way to display the photo
If you want to read more about it, here is Google's documentation about contact photos
This is a rather old question, but nevertheless I hope this can be helpful