I thought all the lessons would be audio such that you could listen in your car or with headphones while working out or walking but some require you to read and hear. I think even alphabet, numbers and grammar can all be made in an audio version. Also, I do not like the fact that you can’t stop and review an audio lesson. At least on an iPhone you can't just stop a lesson and go back to the beginning. You have to let it play out until the end to start over.
Response from Rocket Languages
Hi Looman - Thanks for your review. The grammar (Language & Culture) lessons have a lot more English explanations and tables that don't work well as just audio. On the iphone app, you need to expand the player at the bottom of the screen. With that you can use the slider to move through the audio!