Learning Mandarin is very hard. One of the many reasons is pinyin. Some students may protest, pinyin is easy to learn, and it is so handy. MSL Master teaches pinyin as well! Yes, pinyin is very handy, and we use pinyin in our Mandarin Express Intro and Basic Levels. We fully recognise the usefulness of pinyin at the beginning of learning Mandarin. But, in the long run, pinyin creates more problems than it solves. The trick is to know when to stop using it as the only means of instruction.
For zero beginners, pinyin makes Mandarin accessible and approachable. Students can get a hang of it quickly, and be able to speak some basic Mandarin without any knowledge of Chinese characters. But if anyone wants to successfully go pass the beginner level, they have to resort to learning Chinese characters, the Chinese writing system.
Pinyin has three major problems.
First of all, it is so confusing. That many Chinese characters have the same or similar pronunciations leads to so many pinyin syllables look the same or are with minor differences.
Secondly, students cannot ground meanings into pinyin, as they can do so with characters. For example, 事 and 是, the pinyin spellings and tone markers are the same. With one glance at the two characters, one knows their meanings instantly. But putting their pinyin side by side, no one knows which is which.
Lastly, most people know that Chinese characters don't give clues on how to pronounce them. Worse than that would be that pinyin gives a false sense of fixed pronunciations. It fails to reflect variations of pronunciations of the same Chinese character as well as tone changes in natural speeches. Relying solely on Pinyin gives an incorrect impression that there is only one standard of "correct pronunciations and tones", that all Chinese people speak according to this standard tonal script. And of course, they don't. Regional accents are real and fun to spot. A person with a Shandong accent speaks differently from a person with an Anhui accent. Neither of them speaks according to the standard pinyin. If we pick 100 people randomly from China and ask them to read aloud some Chinese words, we probably hear 100 different pronunciations. However this regional accents do not prevent them from talking to one another.
Therefore, we highly recommend all students start slowly on learning Chinese characters. Once they reach a critical amount, such as 300-400 characters, they can shift the focus from learning through pinyin into learning through characters.