I wouldn't expect too much from this event. I'm glad they're doing it - FFXI has a long and storied history, and it's nice to see it getting its props as it winds down to retirement - but the Rhapsodies story is clearly being done on a shoestring budget. Two of the three new zones added for Rhapsodies are literally greyscale versions of existing zones, for example, and one of the new Prime Avatars, Siren, is so clearly a modified Garuda model that even one of the in-game characters thinks it's Garuda at first blink. I wouldn't expect a whole lot of resources to be spent on the crossover event, either.
The writing for Rhapsodies is a bit weak, too; it's a little too obsessed with its lead character Iroha. She comes from a Bad Future where the world has been all but destroyed - but rather than work toward solving that problem, the player character seems to be spending all their time trying to figure out how to save Iroha. All the world-saving really seems to happen almost accidentally around us. We're seeking out powerful beings; Prime Avatars, Cait Sith, Gra'viton - and when we meet them, do we ask how to save the world? No! We ask how to keep Iroha alive - and then the villian coincidentally shows up and we confront them.
I also wasn't pleased with how they characterized some of the Prime Avatars. We meet with Odin and Alexander, for instance. The former has always been characterized with a near insatiable lust for battle. It's pretty much all he ever talks about, either encouraging people to do battle with him or empowering them to do battle on his behalf. The latter, while getting much less dialog prior to Rhapsodies, had a creepy cold, emotionless vibe to it, like an all-powerful god computer programmed to extract worship from its subjects by any means possible. In Rhapsodies, both entities have bland, normal conversations with the player, with the only hint of characterization being to sprinkle Thee's and Thou's into their speech.