Well, nothing major. They fixed various glitches and crap, but also introduced a rather profound gameplay bug with 1.1 that bugs me to this day. In 1.1 and on, attacks that cause 1% or less damage have hit lag. Attacks that consist of a series of such hits are always escapable by the opponent if they hold certain directions. To tournament players like me this is horrendous (I use Zelda), but casual players will barely be affected.
Major changes were saved for the PAL version.