Mobile eCommerce applications are increasingly becoming popular for shopping online in Africa, since the means of accessing the Internet is mostly through mobile devices. This presents an opportunity to explore and understand the key issues affecting African mobile eCommerce applications by performing sentiment analysis of users reviews from seven top African mobile eCommerce applications (i.e., Jiji Nigeria, Jumia, Jiji Kenya, Konga, Takealot, KiliMall and Jiji Uganda). We implement two sentiment analysis approaches, which are Linguistic Inquiry Word Count (LIWC) and Machine Learning (ML), to classify user reviews into positive or negative sentiment polarity. Specifically, we compare five ML algorithms and the LIWC with respect to their performance, and also conduct thematic analysis to uncover the positive and negative factors affecting African mobile eCommerce. Our results show that LIWC is the best performing method with 86.7% F1-score. Our thematic analysis reveals various business, legal, and technology issues, as well as positive factors such as ease of use, fast delivery time, and affordable items. Finally, we offer recommendations on how to tackle the negative issues.