The "lower decks" concept has been executed well -- but not by JMS.
The Lurker's Guide discusses the details here.
This is, hands down, my least favorite episode of Babylon 5, and there are two main reasons for my antipathy. First of all, Bo and Mack are not interesting characters; basically, they are Marty Stus for JMS and Harlan Ellison, and as such, they talk about things that only JMS and Harlan Ellison find fascinating and/or funny. For instance, they spend at least a minute in one scene discussing spoo and whether or not it tastes like chicken -- and this conversation takes place, oh by the way, while the station is prepping for an alien attack. WTF? Why the heck should we care about the taste of spoo if the station is on high alert? Why the heck would you slow down the entire plot just to meditate on that morsel of trivia?
Secondly - and perhaps more importantly - the "outsider perspective" Bo and Mack provide with regards to the leads is a one-note perspective. Some negative rumors are mentioned here and there, but they are quickly brushed aside to make room for the encomiums to Sheridan, Delenn, Franklin, and even Lochley (the new kid on the block) and their unbelievable awesomeness. Now, I'll grant that Sheridan, Delenn, et. al. are heroes, but - as you should know if you've been reading my B5 reviews long - it really chaps my hide when JMS invades his own work and starts to tell us that his creations are magnificence incarnate. Sheesh! Talk about bleeding all the humanity out of your characters!
And thus, in closing, I shall leave you with the following quote from another one of my Live Journal posts:
All observations regarding Londo and G'Kar and their obvious chemistry aside, I despise this episode above all others for continuing the invasive themes that were clearly evident in The Deconstruction of Falling Stars and nascent in earlier episodes - and doing it in a painfully unfunny way. This is meta that fails spectacularly because it is, at base, completely self-serious - and there's nothing worse than self-serious meta that tells you what to think.
I thought about awarding JMS a point for the one or two decent bits you can find in this dreck (like, for example, that scene between Londo and G'Kar) -- but then I decided I resented the waste of time that was the rest of the episode far too much to be that charitable.
As far as the performances are concerned, this is a very average episode.
The message is also pretty neutral here (thankfully) -- and that's what prevents this episode from achieving "inverse feature" status.