Babylon 5 was an ambitious undertaking: a set plot arch taking a certain number of seasons to complete and with planned, patient internal character development. Unfortunately, three things kept me from buying into the series:
First and foremost, I found the low production values so thoroughly distracting that it was difficult for me to focus on the show. I have worked on theater set and costume design and construction, and even on a nearly non-existent budget my group consistently managed to overcome lack of resources with stunningly creative artistry. B5 is a show with passionate people behind it, but they seemed more interested in improving the abstract (multi-season plots) than in the concrete (sets and costumes that don't detract from the environment). It was another theater buddy, a huge B5 fan, that insisted I watch through the series (and enabled me with disks). He loved the show for the grand vision, I couldn't for the lack of attention to nuts and bolts. By the end of the show they had improved to a mid-level, but that was too late for me.
Second, and not necessarily a lasting criticism, more personal preference, but the show also featured a more theatrical, slightly exaggerated style of acting that I dislike in a television setting. There were some shows that got away with it somehow (SG franchise, Joss Whedon shows), but unless you're doing tongue-in-cheek, self-referential humor, it really takes me out of the moment.
Third, the politics. I know, the whole show is built around politics and diplomacy... but they were SO STUPID. Despite my earth-bound preferences, I was highly educated (Latin, philosophy, literature, politics, all that jazz) and I could not get past the naive, fantastical, imbecility of the B5's diplomatic and political threads. If you want a well done (though still a bit naive) science fiction political narrative (outside classic literature), check out the Ex Machina graphic series.
I can see the appeal behind the series, and I understand why my friend loved it so much, but these three notes hit the wrong chord for me. I'll spend my viewing time with my Clint Eastwood flicks.