I started using Rocket Chinese in February (when I first began my Chinese studies) and it has helped me enormously. I highly recommend it to both beginner and intermediate students looking for fun, interactive lessons.
Each interactive lesson lasts about a half an hour. I do about 3 or 4 lessons a week. I prefer to complete the lessons online where I have full access to all the supporting resources, quizzes, notes and study aids, though you could download the audio files to your iPod or iPhone.
I have to admit that I found the first few lessons a bit intimidating. I was starting as a total beginner and I think the tonal aspect of Mandarin Chinese threw me for a loop. But once I grasped the basics, I really started to enjoy the course and made fast progress.
After a number of lessons, the hosts David (an Australian fellow who speaks fluent Chinese) and Lin Ping (the native speaker) started to feel like old friends. They have a very encouraging way of presenting the course material.
If you’re looking for an interactive course to help you learn Chinese faster, check out Rocket Chinese.