One of my all time favorite shows. But that says, it certainly has some major flaws. First, the first season can be a bit dull to get through - it laid the groundwork for the remainder of the show terrifically, and the things it sets up pay off big time later on, but its the type of thing where someone might be tempted to give up before making it through that first season. Second, the special effects were quite good for their time but might look a little dated now (then again, the original Star Trek's effects look dated now too and yet there's plenty of things to still like about it). Finally, the acting and quality of the dialog can vary quite a bit. B5 features some of the best actors I've ever seen on TV, like Andreas Kastulas (i.e. the one armed man from The Fugitive) and Mira Furlan (i.e. the "french woman" from Lost), but also there were some actors especially in season 1 that were a bit wooden. And while B5's writing is terrific in terms of themes and stories, sometimes the show's dialogue seemed poorly written to me (other times very well written, though).
But enough about the negatives. The strengths of the show are its themes (order vs. chaos, light vs. dark, choices & consequences, and others), the way the major elements of the plot were planned out from the get-go, which is why things that happened in season 1 paid off as late as season 5, and the overall story. The show's unanswered questions and mysteries tended to be quite layered and revealed slowly over time.
Would I recommend it? Absolutely.