Audio is the most important and hardest component of learning a language so apps have a huge advantage over textbooks any day. I really don't think recommending textbooks is at all relevant these days. Graded readers are better for simulating immersion. Apps are better for getting your feet wet. Textbooks can teach grammar but so can apps and really you have to be pretty far along for grammar to be the main stumbling block (over listening, pronunciation, and vocabulary).