Suikoden III is among the most ambitious story rpgs in the last 15 years. On that front, it is as good as ever. Though the final section of the game is flawed, story-wise, due to the departure of the series creator and it has an abrupt ending (non-108 ending). Still the story and characters are as great as ever.
Combat-wise, I think it's one of the more unique and memorable battle systems of the ps2 rpg era. You said yourself you got stuck. It's an rpg where you would get stuck depending on who you took with you. On that note, the gameplay is as good as ever.
Where Suikoden III flounders is the technical side, which wasn't admittedly good when it came out, but it was tolerable when we had sdtvs and stuff. The character designs an cutesy style are charming, but certain sections have hideous frame rate (notably Vinay Del Zexay), and the graphics are pretty plain to look at now. Suikoden III isn't for the person who is put off on technicalities of a game. What game is there is still pretty great and still the most ambitious story rpg in the last two decades. If you can live with this...
You can play Suiko III.