I've never understood why this episode is considered the worst of the lot. OK so the Zarg is possibly the most unrealistic monster ever to appear on the show, but ignore that and the episode is pretty good in my opinion.
It has two main plotlines - the slightly comedic plotline of Garibaldi searching for the missing maintenance man, and the more serious and plot-important plotline of Delenn being made Entil'Zha. The Garibaldi plotline is entertaining but somewhat immaterial to the run of the series, but Delenn's plotline is important to the series for two major reasons: 1) it's integral to Delenn's personal journey and 2) it is an important point in Marcus' character growth.
The guest stars are good in Robert Englund and John Vickery and the episode has comedy, drama and some action. The best of the bunch? Probably not, but I certainly don't agree it's the worst either.