I found the foundations course the most effective of the four. It will teach you how to read, write, and pronounce the Thai alphabet with step-by-step lessons. Although there is a bit of reading required, you’ll also find basic flashcards, mnemonic devices, and pronunciation drills to improve your retention. Brett also gives practical advice about pronunciation through comparisons between English and Thai phonetics.
Unfortunately, the other courses are not nearly as interactive. If you already know how to read and write, I wouldn’t recommend subscribing just to access them.
The Need to Know and Starter sentence packs include a list of basic phrases for everyday conversation. The basic pack has a few flashcards and explanations, but neither of them have any interactive exercises.
The Talking Thai course contains dialogues spoken by native speakers, but these also don’t have any exercises. Although all of the content would be helpful in everyday conversation, they are probably not worth the hefty price tag unless you are already taking the foundations course.
Ultimately, a one-month subscription to learn how to read and write would probably be worth your while, but for further studies, you may enjoy ThaiPod101.