Don't know about the partially hydrogenated part, because this is the first time I hear of this in combination with guar gum...
Guar gum itself contains a lot of fiber, so it's considered healthy. Some claim it lowers cholesterol and it could help fight diabetes. In some it can cause indigestion, because it promotes bowel movement.
It is widely used as filler in gluten free breads and pastries, so the product is less dry and crumbles less.
Anything specific you are concerned about regarding guar gum?
I found it in the pro complex gainer, and I thought that is like the hydrogenated oiks which cause cancer etc