I liked Superstar Saga, but as I don't have a DS (at least not yet), I'm quite restricted. Probably, Partners in Time has an improved battle system, but that was my main source of complaints in the previous title: sometimes you were punished too harshly (read: the enemy took away a chunk of your life, something that could have been avoided with timing) because of one wrong pressed button. I hope the changes are for the best.