The story behind Michael O'Hare leaving B5 is really depressing:I'm up to about half way through season two, and still enjoying it! Most of the main characters are pretty interesting, the only one I'm ambivalent about so far is Talia. It's also taken me a while to warm up to Sheridan too, but he's been getting better. I still prefer Sinclair though!
And then if you look at the rest of the actors, you'll find a lot of depressing stuff. A lot died at 60 or earlier.
I was lucky enough to hear them at Phoenix Comicon for the anniversary. I didn't expect so many to die since then.
Here's that panel. It's really good: