I'm sorry, but I disagree about the review and I'll be sincere about it: It's a bad review.
First off, you're ****ing spoiling the story of the second game by telling what is the objective: To light the lighthouses. That isn't mentioned until *SPOILERS* you reach Lemuria and talk to its king *END SPOILERS* so you're basically saying the actual objective of the game.
Second, it's The Lost Age, not The Lost Ages.
Third, *SPOILERS* Isaac is the one trying to stop Felix from lighting the lighthouses, not the other way around. You can't say "stopping Isaac from stopping the lighting the lighthouses, and light them". It doesn't make any sense (Isaac and friends don't just "stay around" the Wind Lighthouse until you get there, they actually pursue Felix).
Now, you're not even specifying why would the lighting of the lighthouses save the world (yes, it's spoilers, but you've already spoiled it so what's the point in containing more secrets?). You're not mentioning the hugest point of the non-battle gameplay: The puzzles. You didn't say anything about the Djinn's battle cycle (Standby->Summon->Recovery) which should be specified more than "with a special timing system to do multiple attacks or special super attacks. You can also summon incredible attacks by using your djinn's abilities"...
The music is actually better in Golden Sun: The Lost Age than in Golden Sun. There are more themes, and many themes from Golden Sun return in the sequel. Not to mention you can listen to all of both games' songs in Golden Sun: The Lost Age...by the way, I know it's my opinion and all that but Golden Sun: The Lost Age has more diversity than the original (admittely though, the first one has the Venus Lighthouse theme, one of my all-time videogame music favorite themes) and I think that would make it "better".
Where's the multiplayer aspect of the game? And what about the Battle Arena? Since you don't mention them, probably they don't exist...
And graphically, both games (especially the second one) are the TOP of what the GBA can bring. I mean, from all of the GBA games I played, none matched the Golden Sun series in the graphical department. Both games deserve a ****ing 10.
Finally, the second game being worse than the original is your own opinion, but I think that it logically isn't any worse. It's got the same battle items, djinns, spells, classes and such as the first game, and they add up A LOT on top of that. The game is much less linear (at least, until you first set sail, but even then there are many things you could miss if you're not careful), you can use the same characters as in the first game, it's got (far) more extras and the dungeons are more complex and the bosses, harder (except the final boss...but I think that was because I was overpowered). And...the game lasts a lot more than the original...
In my book, both games deserve a straight 1 and a round 0. 10. The second one being an 11, or the original being a 9.5.
In conclusion, I find your review to be extremely flawed. Try harder next time. Good luck!