I work in the loop and have been here multiple times for lunch. Service is fast but lacking friendliness because there are just so many people waiting for a table at lunch time. It usually takes less than 5mins to get your food after you order. From time to time Siam Rice will really surprises me and I'll feel like they got my order out faster than a fast food restaurant. How is that possible.
If you're not there at 11:30 be prepared to wait wait wait Prices are decent for the amount of food you get. And most of the dishes I've tried are taste pretty. One thing I was not a fan of was that the restaurant tries to fit in any many tables as possible in the space they have. You could be sitting comfortably at your own table but you will feel like you're sharing a table with your neighbors. That's how close everyone is packed in and this makes for getting up and not bumping in to any one else difficult. If you are conscious of your personal space this may be troublesome for you. I would definitely recommend this Siam Rice over other Thai restaurants in the loop but be prepared order right after you sit down, be crammed in, and eat fast! Enjoy.