Here's some video of a gigantic Blacktron city, taken from a LEGO convention a couple of years ago. Pretty impressive stuff. Adding the Men in Black theme by Danny Elfman was also brilliant.
Blacktron was always my favorite subtheme. Not only was it the first subtheme from the greater Space theme, but it also happened to be one that was a bit more sinister, a bit darker and edgier; these were the first LEGO "bad guys" that I know of. Nobody knew exactly what made them bad, but the fact that the paramilitaristic Space Police line-up had to lock these guys away in those little prison pods, plus their dark, pure black suits, and their nearly black trimmed with yellow like some kind of dark hornet color scheme for their vehicles made them attractive all around. In general, LEGO Space fans tend to be quite fond of the original LEGO space villains.
I'm not sure what all the marching Classic Space minifigs are up to. Are they attacking Blacktron? Are they Blacktron agents getting ready to infiltrate the rest of LEGO Space? Or is Blacktron on friendly terms with them in this scenario, and has invited them to come by via parade? I have no idea.
As an old timey Space fan, I'm also quite jazzed about the Galaxy Commander in variant color schemes at about 1:07 on the video. There's an original Galaxy Commander, but there's also one in Ice Planet colors, one in M:Tron colors, and one in Space Police I colors. All four are excellent.
The only thing that's actually somewhat disappointing it seeing row after row of the same vehicles parked. That's realistic, after a fashion... but somewhat boring.