Incredible writing. You know those television moments that seem fake, artificial and constructed without much coherence? Fear not - you will get almost none of those with B5.
If you like something of substance that honestly tries explore what the near future could look like for humans - this is it. You get to watch it start and you get to watch it end.
The story is so well crafted that the writers have accounted for almost any kind of event to be accommodated by the main plot. You can not understand that when watching the show as everything is running smoothly. The script was so well written that they could have and on occasion they did write off characters and actors out of the film with practically no damage to the series.
Acting is not the one crafted to artificially impress the audience - but the kind where things go naturally.
The series is more about social development than sci-fi. So if you need the constant flashy cgi bits and ludicrous stunts. Its not for you.
It is the finest show I've ever seen in my life. Even people who dislike the substance compliment it on a job well done.