I went in the evening and it was crowded. You could barely see the lions, plus they didn't do much. It was cool that the trainers tried to play ball with them which made them a little playful for a few minutes. I'm glad it was free but overall boring.
There are lions here, but the "habitat" is small and not especially inviting. Usually the lions are asleep anyway. It's free, but here you get what you pay for. If you want to see animals on The Strip, Siegfried and Roy's Secret Garden is notably better.