Skyscraper I think is an underrated album overall. It was definitely uneven, not the straight forward rock that Eat 'Em and Smile was, but the good stuff was really good, like Two Fools a Minute, Hina, and Damn Good. The song Skyscraper was pretty creative too. And those were some of the songs Vai was behind the writing on.
But then you had more of the pop direction Roth was headed in, and I remember Steve talking about when David presented him "Just Like Paradise" and Vai was like, "what the heck do I do with this?"
I caught the Skyscraper tour for a few shows, it was uneven too. Vai still brought it for sure, but I really missed Billy being there.
Overall though, Roth was a product of his times, and like so many artists from that era, it was game over in the 90's. Plus the double whammy he wasn't a young lion anymore. Plus by the VH reunion era his voice really was shot. I still think Geoff Tate out creeps him on the weirdness factor at this point though.