He's beautiful. Definitely a sighthound mix. I wonder if he has ibizan hound, his face makes me think of ibizan more than saluki.

http://en.wikipedia.org/wiki/Ibizan_Hound

http://www.dogbreedinfo.com/ibizanhound.htm

But then mixes can always look so unique. I don't think he looks too thin really, just sighthoundish. They often look somewhat slender and ribby. I suspect as he settles he'll be more interested in his food too. Hope we get to see more of him, he's really a total cutie!