I have been a member for almost 15 years and of all the organizations that are available for Wildlife Rehabiltators, IWRC is the ONLY one that is 100% science based. That means that every class that is offered online or in person and every symposium that they host is reviewed for content, so all information taught is the most up-to-date and best, safest practices in the field of wildlife rehabilitation. Many other organizations do not go this extra mile and therefore much of what else is presented in this field is anecdotal and potentially unreliable, and can be misleading; unknowing wildlife rehabilitators may be ill-informed by another organization. But not IWRC, I always know that I can trust any presentation or publication backed by IWRC. In addition there staff is professional, respectful and reliable. I highly recommend IWRC to all wildlife rehabiltitators, in my opinion it's one of the only organizations in this field that can be trusted for professional training, expertise and helpful staff.
IWRC has a great mission however I feel that they do not offer much in terms of membership. I feel that out of all the non-profit orgs that I belong to, IWRC appears to not do so much. I've been a member for a couple of years now and it looks like their training and certification program is at a stand-still and they don't offer as many in-person classes like they used to. I may think twice before renewing my membership again.