Get unbiased advice before you buy. The majority of people go there for take-out, rather than dining in.
Decoration is definitely low-frills.
It's easy to miss Mae Phim. It's a tiny restaurant, hidden away from the main street. It is worth searching for, as their menu is a wonderful mix of tasty and inexpensive. They carry a wide variety of dishes, but I've only tried a few, because the ones I've ordered have been of such high quality that I find myself re-ordering them. You should confirm all information before relying on it.