So, first off, I'm biased because AJ's was my favorite Vegas steakhouse for years. I ate here one time before but it was right at opening so I reserved judgment.
Got a comp for 2 last week after a marathon gambling session. Both got the ribeye, an app (salad, kobe meatballs), and two sides (asparagus, cream spinich).
Best thing I can say about the above... good not great. It certainly has a hip vibe fitting with the rest of Hard Rock so I'd reccomend it if you're already staying at Hard Rock and either have an expense account, a comp, or just craving a high end steak and don't want to leave the property.
There's really not much reason otherwise.