Thai Lahna is one of my favorite restaurants. We go there at least once a month, sometimes more. Their food puts every other Thai restaurant to shame. I always get the Phaht Sii-iiw Neua and my fiance gets the Panang Curry. I always want to try other dishes but then I remember how good Phaht Sii-iiw Neua is and can't say no to that. The noodles are fresh and the dish is spicy, but not so spicy that it overwhelms the flavor.
The only issue with Thai Lahna is the service. We've stopped going in and just order Take Out now because of the service. We either get really awful service, super slow service. The one Thai server that we've ever seen is actually really nice, but the others are so rude. Thankfully the food is amazing, otherwise we would not get it.
I thoroughly recommend trying Thai Lahna, your life will be incomplete without it. However I also recommend just getting it for take out. If you have to eat-in, do not sit in the corner, you will never be served.