That works, but it is unnecessary, since \ and % are complements, in a sense, and cancel each other out: % dereferences a hash reference ($value), i.e. gives you the hash it references; \ then gives you a reference to this hash again.

There's nothing wrong with doing it this way, but I encourage you to get a good grip on references (hash or not). You'll often encounter them in Perl, and nested data structures don't work without them at all.