Structure is a full featured Sampler and the tool of choice for typical sampler works for many pros until today. It is interesting to see that most semi pros today know Kontakt and others, but not Structure as it much better fits into many scenarios today where other samplers are typically used which are much more CPU and RAM hungry and have a much more "sophisticated", time consuming workflow to the same result.
Out of the box it has functionalities which are not to find in other so called "samplers". As typical for AIRs pro instrument products Structure allows very professional work with a fast to learn and flying workflow. For me - Structure (i did not know details about Structure LE) is a definitely must in every Pro Tools DAW.
Who is just looking for a complete sampler (and not mainly a "sample pack player" like Kontakt & Co) and even after a high quality effect and tweaking section to do his work Structure is definitely worth to take a look at.