We learn a lot more about the Minbari here, both in terms of their reverence for "true seekers" (at least among their priestly caste) (and how Delenn sees Sinclair), and in terms of how they (or again at least Delenn) is perfectly happy keeping secrets from others if it will make the universe click along the direction she wants it to. We also learn that Ambassador Kosh is monosyllabically pleased that the air of mystery about the Vorlons is intimidating. And we get more indications that the Centauri Republic is bureacracy-ridden and not terribly effective.
Plus we get the first all-CG creature on B5 (and one of the earliest I can recall seeing on any TV), and it's pretty impressive for the era.
David Warner, as Aldous, lends passionate gravitas to the role, and his origin tale as a corporate accountant is very nice. The other major players (Tom Booker as Jinxo, William Sanderson as Deuce) aren't quite as convincing, but they avoid tripping over the furniture in an adequate fashion.
The ep is not without a raft of low-level flaws that drag it down. Deuce feels like a fairly low-level thug, but is treated as a serious crime threat in Downbelow. There's a fair amount of humor in the episode, but it's utterly defused by overly-cutesy comedy music (which JMS was apparently quite unhappy about). The blocking in the final confrontation Downbelow (especially the Fateful Shot) is awkward. And Londo's cowardly buffoonery is cranked up just a notch over what plays realistically.
The discussion about "seekers" — and what makes a man look for something that even he acknowledges may not exist — doesn't quite rise to where it feels like it should be, driven out by the Deuce conflict, and where it does come up it usually feels a bit mawkish. A shame, because it should be a significant element for Sinclair and his place in the B5 world (if not in discussion about B5 itself).
I do still like the whole idea of Downbelow, and of the folks who come to B5 and simply cannot make a go of it ending up as "Lurkers" in the equivalent of crime-ridden shanty-towns. It never fully gels in the series, but it's a useful story construct that's used to reasonable effect, and gives B5 a grittiness that a lot of similar shows before then lacked.
Most Dramatic Moment: Aldus last testament.
Most Amusing Moment: Though this could be "Most Arc-ish" I'll put it here: Ivanova's "Boom" speech at the end.
Most Arc-ish Moment: Jinxo relates the fates of the first four Babylon stations, and his relationship to them. We'll come back to that soon enough …
Overall Rating: 3.5 / 5 — nothing wildly impressive, but a pleasant thing to view, esp. after "TKO".
Lurker's Guide: http://www.midwinter.com/lurk/countries/us/guide/015.html
Babylon Project: http://babylon5.wikia.com/wiki/Grail
That was my absolute favorite moment of the show.