This work explores the impact of teacher-led heterogeneous group formation on students' teamwork, based on students' learning styles. Fifty senior university students participated in a project-based course with two key organizational features: first, a web system (PEGASUS) was developed to help students identify their learning styles and distribute them to heterogeneous groups. Second, group facilitation meetings were introduced as a technique to help students reflect on their weak/strong traits and employ appropriate roles in their group. The study research questions focused mainly on students' attitudes regarding the learning style-based group formation approach. By applying qualitative research method students' views were recorded about the impact of styles awareness and group heterogeneity on group collaboration and possible benefits and drawbacks related to the style-based grouping approach. Evaluation data revealed that students gradually overcame their initial reservations for the innovative group formation method and were highly benefited since styles heterogeneity within the group emphasized complementarities and pluralism in students' ways of thinking. Overall, this work provides evidence that the adoption of learning styles theories in practice can be facilitated by systems for automated group formation and supportive group facilitation meetings that help avoiding the trivial and discouraging approach of using learning styles to simply label students.