In my opinion, the key features of IFS are the following.
1/ IFS is evidence-based by the National Registry of Evidence-based Programs and Practices.
On a personal note, I have been using IFS since I went to an IFS therapist in 2016. I have been practicing on my own after that and have relied on its guidelines ever since. To this day, it is my go-to therapeutic modality.
2/ The language of IFS is not pathological.
Psychoanalysis has a very harsh vocabulary, especially coming from Freud (castration, autoerotism, death instinct, penis envy, …). This might not be obvious for people who have not been in therapy, but being at the receiving end of this kind of language can make matters worse. As a comparison, IFS will use expressions like “How do you feel about this part?”, “Ask the part about what makes him so angry and how he can trust you”, “Let this part know that you want to get to know it when it’s ready”, “Say thanks for that he told you that” (taken from Sample IFS session). This difference in language greatly facilitates the therapeutic effort on both sides.
3/ IFS is led by the patient, not by the therapist.
The role of an IFS therapist is to support the patient in establishing trust with his own parts. Therefore, it’s up to the client to describe what is happening in his inner world. The role of the therapist is limited to assisting when the patient does not know how to progress and making sure that the client re-establish contact with his parts in a positive manner. In rare cases, the therapist might interfere as it happened to me once.
4/ IFS relies on the quality of presence of the patient and therapist.
A central aspect to IFS, which I have kept aside to not introduce confusion, is that the session must be guided by the patient’s Self (and assisted by the therapist’s Self). The word Self here means “The core of a person, which contains leadership qualities such as compassion, perspective, curiosity, and confidence. The Self is best equipped to lead the internal family” (glossary). Therefore, a lot of effort and precautions are taken to guarantee that the quality of presence is as close as possible to the Self. In practice, the quality of presence of the Self is described by the 8 C’s: Calm, Connection, Compassion, Creativity, Clarity, Curiosity, Confidence, and Courage.
Following the previous points, the potential for transferences and counter-transferences is significantly reduced compared to most therapies.
Note: in my experience, the most important limitation of IFS as a therapeutic modality is—while a part can be felt and released inside the body—it is generally inferior to therapies based on the body. For instance, I have found Somatic Experiencing to be a better modality to release trauma stored in the body.