With the introduction of Generative AI (GenAI) tools such as ChatGPT, the educational environment has completely changed and university students now have tremendous access to individualized learning resources. This work aimed to investigate the opportunities, risks, and constraints that university students can encounter due to the use of resources produced by GenAI. In particular, the study determined which GenAI tools students use the most, evaluated their effects on the learning process and critical thinking, and writing skills. This study used a mixed-methods approach, combining quantitative surveys and qualitative interviews to obtain in-depth information from a wide range of students in Rwandan universities. In addition to demonstrating the advantages and disadvantages of using GenAI tools in higher education institutions, the findings will provide educators, and students practical suggestions for enhancing the safe and efficient use of these technologies in the teaching and learning process. As results, it was revealed that 80% of respondents were aware of the GenAI tools while only 20% not aware. The most used was ChatGPT where, 65% of the respondents said they mostly use it. Gen AI tools are mainly used for research purpose 51% and have helped them to improve their academic performance.