This study aims to analyze the evaluation of use and usefulness of the eNego electronic negotiation system from both subjective and objective perspectives. The subjective evaluation is based on responses to questionnaire items inspired by selected elements of the Technology Acceptance Model, specifically perceived ease of use and perceived usefulness. The objective evaluation stems from the analysis of the accuracy of scoring systems created by negotiators in eNego. To achieve this goal, we utilized experimental data from the series of eNego experiments. The analysis employs descriptive statistical methods and k-means clustering to identify distinct user profiles that capture similar subjective evaluations of eNego, as well as to explore the relationship between these profiles and the scoring system's accuracy. The results provide valuable insights into user preferences and the overall effectiveness of the system. The analysis of user interactions with the eNego system revealed varying evaluations across four user groups, determined by k-cluster analysis. Initial inaccuracies in the negotiation scoring system were improved through an iterative pre-negotiation mechanism, ultimately leading to comparable accuracy levels across all groups.