Hillstone is good... but it's not Houston's. I was devastated when i found out they are closing the Houston's in Scottsdale next year and heard that Hillstone is basically the same, (it replaced the Houston's in Phoenix). I work right across the street, so finally I figured I'd give it a shot.
The restaurant is beautiful, the staff is nice, but the Caesar salad (my favorite) was terrible compared to Houston's. There was corn in it, which I'm not totally understanding and some larger clumps of lettuce that made the salad uneven and harder to share. I'm afraid to try to the burger... but in fairness, the salmon appetizer was just as good.
CONCLUSION: Don't close Houston's. It's better. End of story.