The 717 is a solid, reliable airplane with a pretty nice flight deck, however I like the way Boeings fly better. It does not feel as solid as Boeing on the controls and is unstable at slow speeds in comparison.
Hawaiian Airlines flies the crap out of them-12-16 legs a day doing 30 minute turns.
More than likely the reason to retire it was financial, perhaps not enough orders or a higher margin on the 737 line.