I enjoyed Spirits Within, had a good interesting story.
It might have had a better reception if didn't carry the FF title.
SE's marketing was never any good, but this was the f_ck up of all f_ck ups on their part.
Putting the "Final Fantasy" title on a piece that was completely different than all previous FF's, especially FFVII
(the title that broke them out into the mainstream and was relevant at the time as well as responsible for the conversion of new FF Fans)
, was counter-intuitive. On one side, they achieved their goal of driving all the FF fans to theatres. However, they also upset and disappointed their fans as a result. It is one of their biggest blunders ever, second probably only to FFXIV 1.0.