The best character in ER history is on her way out ... again. Sherry actually left the show in the middle of Season 3 and returned at the beginning for Season 8. Dr. Susan Lewis remains a fan favourite (certainly mine) of ER and with her out the door again (along with Noah Wyle), ER will certainly be different.
But can you blame her for wanting to leave? Over Season 11, Sherry was ridiculously underused. This fantastic actress never got her chance to shine over the past season. However, I can see Sherry go onto great things (for some reason, I imagine her on 24) and I wish her the very best of luck on where she goes from here.