DC2 is _great_
the first one sucked, imho, but parrt 2 is a very safe bet. if you don't mind a paper thin plot and real time action, you're good to go.
the graphics are exelent, the music interesting and most of the voice acting is well done. i've enjoyed it imensely.
now, as far as other rpgs.. if you like a huge plot Suikoden 3 is fucking _amazing_ (probably the best rpg on the ps2..... sorry FFX)
a lot of people love Shadow Hearts, but compared to Koudelka it was a let down. it's a gritty, occult themed rpg with a very cool turn based battle engine. the graphics are ugly and the voice acting is _bad_ but most people love it.
i have never played Dual Hearts... do this: go to
www.workingdesigns.com and go to the rpg critic. he's views and mine collide but he is an exelent critic.
if you want more info, just ask!