Through research of different online learning Chinese programs, That's mandarin was the one that convinced me the most. I loved the structure of their courses, and the reports they offer to check your overall progress. I also liked the videos that were presented in the classes and liked how they let you switch through pinyin subtitles.
The only inconvenience was the price of the whole program. I think that the company is overcharging for their online services, so it might be very hard for me to go back to complete a level, especially knowing that only one level might cost me around $1300 USD! If I had the money, I'd complete the program. However, I think it is designed for wealthy employees or wealthy students.
If you can afford it, definitely give it a go!