B5 is still one of my favourite TV shows of all time.
The common criticisms are largely true: it does start slow with some weak episodes in season 1, some of the acting is a bit wooden, the CGI hasn’t aged well, season 5 is slightly anti-climactic because they largely wrapped up the main plot arc in season 4 in case the final season didn’t happen.
On the other hand, it had an epic storyline that spanned not just episodes but multiple seasons in a way that no-one had really tried in sci-fi before. That storyline made sense and weaves in and out of the individual episodes because it was planned out in advance. The world-building and development of different cultures and how they relate is generally strong.
Against that over-arching backdrop, it also had a lot of good individual episodes. They had genuine character development. They explored social and moral issues as well as any show of that period. They varied from diplomatic and political settings to the adventure of deep space exploration to almost pure action episodes. They varied in scale too, from relatable stories about a single individual, to stories about a whole planet or culture, right up to the fate of the known universe.
Much of the acting criticism is directed at the main leader characters, but I’ve always thought this is slightly unfair, because the script often relies on those characters to carry the plot and provide much of the exposition and those tend to be the more formulaic parts. The same show also features some of the best acting and main character arcs in TV sci-fi, with the relationship between Londo Mollari (played by Peter Jurasik) and G'Kar (Andreas Katsulas) being one of the great double acts. There were many good moments from the rest of the ensemble cast too, from the doctor wrestling with his conscience to a certain wave. And then there were some great supporting/recurring roles, from the light relief of Zathras (and Zathras, Zathras, Zathras, Zathras and Zathras, of course) to the much more serious Bester (arguably Walter Koenig’s finest work).
If you haven’t watched B5 and you’re a fan of epic space sci-fi, I highly recommend it even with its flaws. The first season is a slow burner (although it also has a lot of subtle set-up that you won’t appreciate until much later) but it picks up. If you’re the type of viewer who can’t stand filler episodes, there used to be some relatively spoiler-free guides to which early episodes you really need to watch and which you can skip, so you could look for one of those. Don’t watch In The Beginning first, though; it’s a prequel TV movie that has lots of spoilers about the main story that you’re not supposed to know yet when you watch the early series.