Most if not everyone that played and loved the previous .hack game (I consider it only one game) probably played it because of the fantastic storyline. It's a shame it ended though. However, GU seems to be even better than the first one.
The battle system is totally revamped. This time they are lending elements from the Tales of Symphonia battle system. It looks really fun. But the most important part of the .Hack games: the story will probably be really interesting. Who is this Kite "clone" (called Tri-Edge) and why do the main characters in GU share the same titles as the Eight Phases from the previous .hack game?
~The Eight Phases~
Skeith - The Terror of Death
Innis - The Mirage of Deceit
Magus - The Propagation
Fidchell - The Prophet
Gorre - The Machinator
Macha - The Temptress
Tarvos - The Avenger
Corbenik - The Rebirth
~Characters from GU~
Haseo - The Terror of Death
Atoli - The Mirage of Deceit
Kuhn - The Propagation
Yata - The Prophet
Sakubo - The Machinator
Endrance - The Temptress
Pai - The Avenger
Ovan - The Rebirth
I want to know more! ;( This will be one heck of a game. I am so anticipating this. More than any other RPG in the making.
Additional info:
http://www.dothackers.net/gu.php