My favourite of ER (perhaps joint with that when Carter and Benton's student kills himself) and perhaps favourite of any show. The acting is superb throughout, and it does seem like it was actually personal to the actors! Ramano's (sp?) reaction when Lucy dies was just so real it bought tears to my eyes, and a massive amount of respect for a character that I was previously having difficulty in actually liking.
The efforts around Carter are moving, and Lucy's final moments and words are somber indeed. Very sad episode, and if you watch it without at least being slightly moved you've got a heart of stone!