SEED Destiny is an utter trainwreck of a series written by a woman whose skills would be more suited to Fanfiction.net
Cagalli - A strong girl in SEED. Likable, brave. Did nothing but whine and pout in Destiny and was eventually shunted to the sidelines.
Kira - Not a bad protagonist in SEED. A bit whiny, but understandable. Then he comes out of nowhere in Destiny with a suit that was pretty much destroyed in SEED, steals the show and acts holier than thou the entire time.
Lacus - Mary Sue incarnate. She was believable in SEED, but somehow pulling an entire private army out of her asscheeks in Destiny?
The Minerva crew - Relegated to antagonist status in favor of the return of the Archangel crew. These guys were *supposed* to be the protagonists...
Phantom Pain - Aside from bringing back Mu for no good reason (Strike 1), these once-promising villains were eliminated midway through the series so that the leads could be the villains (strike 2).