I've been to Nahm on a few occasions for lunch, mostly because they have enough on the menu to please most people.
I'd recommend booking if you're planning to go in the lunch rush as it gets busy.
The decor is comfortable and the service is pleasant enough, if not a tad slow.
The Set Lunches available are a pretty good deal, including ones designed for 2 people (around $130), or the Noodle Set which is $88 for a salad and then a rice or noodle main.
Some of my preferred dishes are:
* Vietnamese shredded chicken salad - tiny hint of chilli, I find it quite refreshing.
* Roast duck salad with sesame sauce - well cooked and great flavours.
* Spicy beef salad with mint and lime - classic, nothing extraordinary but tasty nonetheless.
* Vegetable laksa - could be a bit spicier, but love the overall flavours.
* Thai chicken rice - looks a lot like hainese chicken rice, but not quite as tasty.
* Spicy glass noodles with seafood - decent amount of seafood and could quite easily go for 2 bowls.
Personally I think it's more of a Chinese take on Thai / Vietnamese, but it's still a fairly decent meal and relatively inexpensive compared to other restaurants in Elements.
My only suggestion is that the waitstaff and kitchen try to coordinate service of food a bit better. On each occasion I've been, at least 1 person at our table has had both courses brought out at the same time and therefore getting cold, while 1 person will have to wait ages for even their first dish.