I think Mongoose is going to do a good job with this. I'm not going to claim that everything they've released has a place in my game, but they have put out a number of products that are extremely good and a few that cover some very interesting new ground (Chronomancy comes immediately to mind). The fact that they were able to acquire the B5 license in the first place, which is really out of the price range of many small publishers (I'm not saying Mongoose is a small publisher BTW), and then put a lot of thought into it, as they appear to have done, indicates to me that they are fans of the show and that it will be good.
I wasn't a fan of Chameleon Eclectic's game, although I do have the two books they put out for it. In my opinion it didn't really do the show justice. The system was overly difficult to understand, the art was... well... crap, and the expansions they advertised never came. In the end it was of very limited scope. It looks and sounds like Mongoose is making a financial commitment to see this thing through to success (or catastrophic failure), so I'm going to give them my support. If I don't like the way that a certain rule was written, I can change it to something I prefer, or change it back to standard D20 mechanics.
Anyway, this is truly a good day for all B5 roleplaying fans. I definitely look forward to the release of this one.