Its strength is in uncovering more about people’s experience (why things may be the way they are).
As qualitative research focuses on small groups, it can be less expensive than quantitative research which may require large groups of participants or expensive measurement tools.
Qualitative research methods collect data about what your select group of participants feel or think, or how they behave. You can't necessarily use this data to make assumptions beyond this specific group of participants.
It is not a research method that conveniently allows for the collection of statistical data. However this is only a disadvantage if your research question also requires statistical data. Adopting a mixed methods approach is one way of overcoming this problem.