I thought she went from evil to good too easily. I think this would've worked better and explained how she could become much more sympathetic (from the trivia section):

The earlier drafts of the screenplay contained more background information on the characters Madmartigan and Sorsha. Madmartigan was originally a knight of the kingdom of Galladorn (the kingdom that General Kael mentions having destroyed to Queen Bavmorda) and that the character Airk was the only real friend he had, but Madmartigan's recklessness got him into trouble, as did his love affair with an Eastern beauty that tainted the family name. Madmartigan had a chance to regain his honor in battle, but he ruined the chance by deserting; this explained some of the bitter antagonism between Madmartigan and Airk. Sorsha was originally the daughter of the king of Tir Asleen, who was a good man (he is in fact the regal old man seen at the end after the fall of Bavmorda and Tir Asleen is restored, and can be briefly seen in stone), which suggested that Sorsha had the capability to be good; during the battle at Tir Asleen between Bavmorda's troops, Madmartigan, and the monster, Sorsha encountered her father and he struggled through the stone to ask her for help, which prompted Sorsha to switch alliances from her evil mother to the good side. All of this was lost in the final film but does appear in the novelization as well as the comic book mini-series by Marvel.