This is by far my favorite Thai restaurant in the city and I've probably made my way through at least 80% of the Thai restaurants here. I've also been coming here for years and have eaten my way through quite a bit of the rather large menu. They also have the best som tum (papaya salad) of any Thai restaurants I've been to here.
The largest plus is that, unlike so many other Thai places, when a white gentleman such as myself say "hot", they actually make the food deliciously, sweat-inducingly hot. But in that regard, I'm a bit of a heat masochist. Medium is still very spicy for most palates and mild even has a slight kick to it -- as it should, mind you.
Also, the area may look a tad run-down if you're not used to Glendale strip malls, but it's definitely safe.