Having been to Thailand many many times... and having actual Thai friends whose families cook like 10 dishes for dinner every day.... I can tell you this place is a WINNER!
The few people here who gave it bad ratings have no clue about Thai food. Lotus is the best most authentic Thai I've had in the U.S. apart from my Thai friends cooking at their homes. I think it's the mom actually back in the kitchen cooking!
It used to be a horror to make a reservation. You would dial 40 times and get a busy before finally having someone pick up and then tell you there is no space. But since they expanded it's a lot easier.
It's also cheap. Best thing in Vegas. Move away from the high priced strip restuarants and have yourself an adventure! And don't be put off by the nasty mall it's in. It's down the row from the infamous Green Door (look it up) plus a myriad of other skanky businesses. Though I always like to go the the gay bar in the strip mall for a beer while waiting for my reservation time I think it's called Badlands.