An essential component of any training activity is observations, and in almost any teacher education or professional development context, observations are followed by feedback sessions aimed at improving teaching practices. Nevertheless, whether these sessions accomplish this aim is an issue of concern as it is highly related to how effective it is perceived to be. This study aims to explore how effective post-observation feedback sessions are perceived by the observed instructors, what factors make feedback effective, and whether feedback has any impact on their practices. Data were collected qualitatively by conducting semi-structured interviews with the instructors and Professional Development Unit (PDU) members. The results showed that the feedback was considered effective by the instructors, and it impacted their teaching practices positively, while helping them with their adaptation to their new institution. The results also shed light on the factors that made feedback effective from the instructors' and the PDU members' perspectives.