I wrote the following Comment on a LinkedIn NIEM Thread and thought it might be worth sharing:
In my opinion (perhaps not so humble :-)) NIEM is very good if you use it right. But, if you think of NIEM as a standard by itself, it is NOT GOOD. Too much stuff. Hard to keep organized. It is actually incredible how well organized it is given its volume, but as a standard by itself, it is just too BIG to be anything but unwieldy.
Now, as a model for building standard exchanges, it has TREMENDOUS value. It is like a mine. You have to refine the ore through an appropriate standards development process. (The IEPD process works for this.) But the ore is super high quality when compared with building standards from scratch, because the NEIM model has been preprocessed in the sense that most definition and relationships are well defined and understood. Even so, you still have to refine NIEM input using the IEPD process to actually create a usable exchange or a useable standard exchange.
Bottom line, if you expect NIEM to be “auto-reusable,” you will be disappointed. But, If you use NIEM appropriately, it has a lot to offer in the way of documented data structure and definition.