Beyond-5G, towards the next generation (i.e., 6G), inspiring plenty of emerging use cases and business models, demands new evaluation for enormously evolving performance requirements of networks. Since the trend of artificial intelligent IoT (AI-IoT) development in 6G tends to leverage more autonomous management with even less human participation, the conventional human-oriented key performance indicators, e.g., quality of service (QoS) and quality of experience (QoE), will not fulfill the demand of things-driven 6G AI-IoT deployment. In this article, we discuss the potential vital emerging performance merit in 6G AI-IoT development, and further propose a novel new measure of 6G AI-IoT performance, referred to as quality of things' experience (QoTE), to facilitate the evaluation of the performance of AI-IoT-based technologies and applications for inter-things network deployment in 6G. Moreover, by defining things-oriented criteria, the proposed QoTE is considered and quantified with the emerging IoT standard (IEEE P2668, i.e., IDex), towards a new era to enable IDex for things-oriented, effective, and objective indexing for inter-things 6G AI-IoT systems/applications.