I eat a lot of Thai food and this is definitely one of the best. And for as much Thai food as I eat, Lotus still had a selection of Thai dishes I had never seen before.
I went with a large group and we ate family style. We got a number of the normal Thai dishes - panang curry, pad see ewe, pad thai, etc. They were all great with one odd exception. No one in the group was a fan of the pad thai. There was something different about it, the color was much darker almost as if they had added some sort of tomato paste (guessing). But everything else was fantastic.
The highlight for me was the thai dishes I had never seen before. There was a short rib in some very spicy orange sauce (forget the name exactly) which was absolutely superb and I will get it EVERY time I return. It is simply fantastic. We also had a unique seabass dish which was good on its own, but great with some other spicy sauce that was served with the dish.
I would highly, highly recommed Lotus of Siam as the best off-the-strip restaurant I've been to in Vegas.