Just so I'm not mistaken for a troll, I'm going to explain why I didn't like Golden Sun that much, since I'm never too busy to point out why this game isn't so great.
The story wasn't that great. Frankly, I remember almost the entire game being a series of sidequests that coincidentally gave you abilities you needed to deal with the lighthouses. Only when one reached the lighthouses did the main story advance. Now, a lot of games are full of a lot of sidequests, and it's perfectly acceptable if done properly. While these games set the bar pretty high for RPGs, Chrono Trigger and FF6 have great sidequests, and the reason why many of them are excellent is because they do some character development. Golden Sun has very little character development and there's almost nothing engaging about the characters. In fact, I don't think anyone could discern who's speaking in the dialogue except for Garet once in a while, since all he does is ask Isaac to affirm something. Speaking of dialogue--there's way too much. Considering there's not all that much going on in the story, it's pretty amazing how dialogues often become 15 minute sequences. What gives?
There are a few extremely annoying flaws with the gameplay. First of all, I found it annoying that if Characters A and B are set to attack Enemy 1, and A kills Enemy 1, B will simply defend. I don't think they've done that since the old FF games. Next up, random battles. This might just be a personal nitpick, but I hate random battles except in games with a fun battle system, like FF6 and 7. Golden Sun's battle system is like a weaker version of FF6's espers. I expected interesting things with Djinn, but there wasn't all that much to note in these battles. You just attack, use djinn magic, or summon. Not much going there. Better games with this type of battle system have thrown in more strategic elements to keep battles refreshing.
GS does have its positive points though. The art, excepting the overworld, is gorgeous. The sound, albeit repetitive in some areas, was pretty ok too. A few tracks were especially good, like the Sol Sanctum theme. Unfortunately, these quirks weren't enough to pull the entire game up.
If I could pick one thing to make the game better, it would absolutely have to be character development. In some games, there's not all that much going on, but the characters keep things interesting. Golden Sun's characters are too static for the story to matter. It really drags things down.
On the plus side, it could've been worse. I'm looking at you, Star Ocean 1.