This paper explores the evolving role of a user within the context of a smart space, focusing on the concepts, challenges, and emerging trends in this rapidly advancing field. As technology continues to surrounding us, transforming traditional spaces into intelligent environments, it becomes crucial to understand the dynamics between users and these smart spaces. This work delves into the foundational concepts of a smart space, which encompasses an environment enriched with sensors, actuators, and interconnected devices capable of perceiving, analyzing, and responding to user needs and preferences. Smart spaces are designed to enhance user experiences, optimize resource utilization, and improve overall efficiency. However, the introduction of smart spaces brings forth diverse challenges that impact the user's. These challenges include privacy concerns, security risks, ethical considerations, and the potential for information overload. Understanding and addressing these challenges are vital to ensuring the successful integration and acceptance of smart spaces in different domains, such as homes, offices, healthcare facilities, and cities. This paper also explores emerging trends that shape the role of users in smart spaces. These trends encompass novel interaction paradigms, personalized experiences, context-awareness, adaptive automation, and the integration of artificial intelligence and machine learning techniques. Additionally, we examine the influence of user-centered design principles, emphasizing the importance of involving users in the development and evaluation of smart space technologies. By studying the concepts, challenges, and trends in the user's role within smart spaces, this work aims to shed light on the transformative potential of these environments. Understanding how users interact with and adapt to smart spaces can guide the design, implementation, and future development of intelligent systems that prioritize user needs, preferences, and well-being. Also we have defined a strategy to evaluate the performance of this concept, namely by accessing the user feedback on the different moments.