In some ways, these occasional episodes that don't feature one of the usual Rogues Gallery are superior to those that feature the Joker, Two-Face and their ilk. With these one-shot villains like Josiah Wormwood, the audience isn't sure what tricks they have up their sleeve, and it adds an element of mystery to the show.
From the outset, when Wormwood traps his prey in quicksand, we know we aren't dealing with a typical "Batman" villain. Of course, Batman changes his tactics to tackle this new threat and the set-up is perfect. When it appears that Batman has fallen into Wormwood's trap, the audience is thrown for as much of a loop as Wormwood is.
The ending of this episode is one of the show's best, in my opinion. The transition of the voice into Kevin Conroy's instantly recognizable tones on "I'm going to WEAR them" sends chills down the spine, and Batman's final kiss-off to Wormwood is priceless.
Not an all-time classic, but it's a solid entry without a "name" villain and a plot that's a bit more elaborate and sneaky than most of the other episodes.