The original Mario and Luigi, similar to the Paper Mario games, was lauded for its original characters and tremendously funny script. From the little of Partners in Time that I got to play (borrowed from cousin for a few hours) the script is as funny as ever, and the game mechanics have transferred to the DS very well. I hope to buy it soon, but I haven't managed to get to a store for a while. If you enjoyed the original M&L, you'll most likely love this game.
Unless you liked M&L for Fawful. "The mustard of your doom!" ...finkrat.