I have that certification. With it having just been added to the BPS portfolio, we may need to give it some time to really judge how it will affect things like it's reputation and desirability. For now, if you are looking at doing any LTC or Hospice work, it would be desirable. Uncertain beyond that. It is great for consulting and can give you a qualifier to be a Clinical Pharmacist Practicioner depending on your location.
I suppose it's usefulness depends on how you plan to use it, like any certification.