I actually sort of like it, although mostly because it's pretty unique. I thought that big 'ball' was simply the power-core of their ships. Shadow & Vorlon ships didn't need this because they drained power straight from hyperspace, as I understand it. And seeing the size of that ball, and considering the heavy shielding on the smaller ships which didn't even have one, I suppose the big ones were close to invincible. Although the Vorlons did manage to push them back.
B5 features so many nice ships that it has much competition, though. Beyond a doubt, the Vorlon & Shadow ships are the coolest, I think. I'm not so big a fan of the EA ships myself, they're way too 'terran' and predictable, typically humans. I like better the exotic ships.
The idea of the Thirdspace movie was good, I think, but the execution was rather poor. The existence of 'Thirdspace', the Vorlon story, etc., was cool. Everyone starting to fight, the Lyta thing, the nuclear bomb, etc., was all rather stupid.