I've played DR1 & DR2 so naturally I'm going to compare them. DR2 took longer to finish & has a lot more to explore. The mini games are harder but I'd say still play DR2 on the max difficulty setting. Yet again you get dual audio options.
Overall looking at the game as a complete package I think DR2 does surpass DR1 & you will get your money's worth. However, while the characters & storyline of DR2 isn't bad I tended to like DR1's better. I might be in the minority but I felt more sympathy for the DR1 characters & the DR2 ending IMHO was a bit flat. That being said DR2 character Nagito Komaeda was an exception – great character!
Hopefully they continue Dangan Ronpa with more games.