Well, I had tried Origin India, Tamba, Bollywood Grill, and India Oven.
None of them compare to the tastes of India Palace that I experienced in Oct 2009. Everything tasted great, from the mango lassi to the chicken tikka masala.
The only negative was that the waiter's Indian accent was very thick and he tended to speak quickly, so he wasn't always easy to understand - even for a well traveled person like myself.
Still, I'm yet to find a better Indian restaurant in Las Vegas.