So if you have a buddy willing to play through 10 missions with you, I really think you'll find it game more enjoyable.
The Dreamcast version improves on the PlayStation version in a number of ways, making frusturating sequences much easier, improving the control, and obviously shining up the graphics a bit. Oh, and not to mention they redid the menus (for better or for worse) and added a competitive multiplayer mode (which is pretty bare bones...but it doesnt hurt).
Jedi Power Battles will go down as my all time favorite Dreamcast game, as playing it Cooperatively with two people is really what makes it enjoyable. Its got enough replay value as well with then unlockable characters as well. Although its unfortunate the unlockable characters dont gain health or force power like the regular characters making it extremely difficult to finish the game as them.
Jedi Power Battles also offers one nice addition, you can play as Darth Maul if you happen to unlock him.
So if you have a buddy willing to play through 10 missions with you, I really think you'll find it game more enjoyable then Episode III, as it has a much more solid control feel, and force power system.