There was a lot of hoopla surrounding the v4 method of collections vs the v3 method of dragging and dropping from one box to another.
Here is why it's cool.
I had made (for example) a collection of "Bible handbooks" and didn't "drag stuff to the "NO" pile" but did it with the limiting wording; you know: subject:bible-handbook, ANDNOT...etc...
Well, upon downloading the HUGE freebie book library yesterday...the new bible hand books that appeared...are already in my collection due to the fact that they match the criteria....no checking, dragging and dropping necessary.
Very cool...