Generative Artificial Intelligence (GenAI) chatbots start changing experiences with art for museum visitors by making them more interactive and engaging. However, it remains underexplored how GenAI chatbots influence visitors' in-field experience and interaction at art museums regarding finding information, engagement, and enjoyment compared to existing museum tour-guide applications. In this paper, we contribute the design and implementation of a smartphone-based chatbot that detects artwork, generates textual and auditory information, and interactively answers visitors' questions. To explore visitors' experience with it, we conducted a field experiment (N=30) at the National Art Museum, comparing it to the existing museum application. Our results indicate that visitors showed higher artwork engagement with the chatbot than the museum application. Moreover, they enjoyed an interactive experience using the chatbot to learn about the art collection and have equally preferred textual and auditory information representation.