Pretty meh.
Its not a really bad movie if it were id have given it 1 star. Its mostly meh.
The worst parts about it are that it fails to address certain plot points from the end of the previous series Gundam SEED Destiny like the protagonist getting millions of civilians killed and it also retroactively introduces multiple plot holes into not only SEED Destiny but the first instalment in the cosmic era timeline Mobile Suit Gundam SEED.
Wouldn't recommend watching sober.