I don't know all that J. Michael Straczynski had to do to produce this epic series but I am glad he did it.
A large number of science fiction series these days suffer from the 'reset button' complex. This means that, while an individual episode might be interesting, it will rarely ever have any effect on any future episodes. A perfect example of this is Star Trek: The Next Generation. In 90+% of the episodes the actions of one episode are completly independant of any other episode. Yes, there are some exceptions (Q episodes etc.) but they are in the minority.
When they moved onto ST:DS9 they improved this significantly but it was never even close to the continuity of Babylon 5.
In Babylon 5 the entire series was a continuous story with only a handfull of episodes that did not have at least some effect on others. The fact that J. Michael Straczynski wrote the whole series beforehand meant he was able to tell the story continuously with few "unconnected" episodes.
Babylon 5 was a 110 episode long story that kept you entertained with fascinating characters who evolved throughout the series. They did not just play a character that had certain traits and repeated them in each episode. G'Kar (Andreas Katsulas) and Londo Mollari (Peter Jurasik) are perfect examples of this. G'Kar goes from the "bad guy" in the beginning and transforms almost spiritually to the selfless "good guy" in the end whereas Londo travels in the opposite direction.
Over all I would give this series a 10 out of 10 with all but 3 or 4 episodes getting a 9 or better out of 10.
"I'll be in the car" Commander Susan Ivanova (War without End)
"Ivanova:Find what you need and lets get out of here, we are running out of time.
Zathras:Cannot run out of time. There is infinite time. You are finite. Zathras is finite. This is wrong tool" (War without End II)