It is hard to beat Busaba Eathai in terms of value for money. Their well thought system gives you the benefit to enjoy tasteful selections of Thai Food in a dimmed, wood dominated atmosphere where you are seated to one of the big square tables. From the menu; Pad Thai, Thai Calamari, Pandan Chicken and the Char Grilled Duck are my personal favourites. I would recommend ordering food to share especially if you are two or three people. The layout is modern; the service is fast, well actually even slightly faster than I would like. My only thing is that their process cycle especially in busy times could push you a bit to leave earlier than you normally would. But it is what it is and perhaps necessary to keep up with the queues building up outside.
In short, Busaba is one of my favourite spots in London. Although the quality of food and the ambiance is similar in all of the branches, I prefer the branch in Soho.