Well, that was a huge disappointment.
Here's to the unresolved plot points-
What the hell happened to Nishi?
What was up with the Vampires? Don't even get me started on how much shit was left out with the Vampires.
Also, we never really got a complete reason as to why Sebastian sent the Gantz technology to earth, I know that he said it was to re-establish order on earth, but that seriously wasn't developed upon.
Nishi's return seemed almost pointless in the end and we ended up getting an insulting, sappy, ridiculous ending full of obnoxious plot convenience. Gantz had a lot of really good ideas but the longer and longer the series dragged on, the more of those ideas got dropped by the wayside. Also Tae is a horrible, underdeveloped, mess of a character.