Background Mothers with severe mental illness are vulnerable and engage with services cautiously due to fears of stigma and custody loss. To develop best practice standards and patient-centred services, the subjective experience of those who use it must inform service improvement and policy. Method This study utilised exploratory concurrent mixed methods design with primarily qualitative data. Women admitted between April 2015 and December 2016 to a newly developed psychiatric Mother Baby Unit (MBU) in New Zealand were invited to participate in this study. Qualitative data were collected in three ways: (i) semi-structured interviews incorporating Māori concepts of health and wellness by research assistants near discharge; (ii) invitation to provide anonymous feedback in writing using an open format; (iii) unsolicited verbal feedback provided during a home visit three months after discharge. Thematic analysis was undertaken. Demographic and clinical information was collected prospectively for mother-infant pairs during the course of admission and three months post-discharge. Results Forty-five people participated in the study. High rates of satisfaction were described. Strengths of the service–as perceived by mothers–included co-admission of mother and infant, staff warmth and availability, transparent practice, inclusion of families, and having a comfortable environment. Mothers described intense distress and confusion, as well as negative self-perceptions when acutely unwell. Infant co-admission and the inclusion of partners and other family members alleviated mothers’ distress. Personal attributes of staff, practical support with caregiving, a range of therapeutic approaches and holistic care were all valued. Feedback collected three months after discharge was the most reflective. Significant inter-ethnic differences were not apparent. Conclusions The experience of inpatient care can have lasting influence on recovery and wellbeing. Employing a Māori model of health broadened the holistic nature of enquiry. The approach and timing taken in seeking the views of participants’ yielded different information, all of which is of value to service evaluation and refinement. The findings suggest that keeping mothers and infants together during health service utilisation such as MBUs should be a priority for policy makers and service designers. This approach is consistent with Māori values, combining the importance of whānau relationships (kinship), wairua (spiritual connectivity), hinengaro (the mind) and tinana (physical health). These findings suggest that ‘holistic care’–in this case following a Māori holistic health model–is important in mental health settings.