well i don't agree, I like Erementar Gerad, the first time i meet the story on some website i thank that the series will be really classic, especially on the characters, but when i see it i change my mind.
yes the love from the begining is bad - like about 90% of series - but except that there's lot of good things, and i really enjoy the journey.

i first see half of destiny before the first season of the series, and after saw the rest of episodes i found (now ep43) so my point of view is different,
it's true that when i see the begining of GS i think of what the sequel is the same, except for the side, but it did not prevent me to watch about 10 episodes a day at a moment.
i was not shock about cagalli cause she s in love, and i dont think she could do lots of thing about orb at the begining, but now she is strong again so ^^
athrun IS a soldier, and it's not long ago than i change my mind about what he choose.
and well... cagalli and athrun are my favorites characters, so i cant blame them easaly :p
i really like the story of this sequel, and i'm a fan, but i'm agree about Muu la Flagaa... and oh my god, i hate Shinn... what a kid ' always waiting he'll be killed or change his mind :p
(i'm enjoying when athrun win againgst him recently :p)

in short, yes there are some similar elements with seed, but there is lots of news too.
I really think that if you have enjoy the first season you will enjoy destiny, perhaps not as much, but it's a good anime