In general, ER is a fast fix. Most patients aren't that interesting. For example, I saw 4 post-thanksgiving gastroenteritis on shift the other day. They were all miserable, and dehydrated, and puking like mad. 90 minutes later, they were thanking me for how great they felt. You see 1-4 patients per shift that are vaguely interesting. You diagnos some fractures, splint them, and sew up some lacs, work-up some vague chest pain (and mostly find nothing, but admit most). You see some vague abdominal pain, that you usually find nothing on. You order some CTs that you are 90 % positive that you won't find anything, but you sleep better at night to make that 10% doubt go away. You are forced to slog through a lot of chronic pain BS. But, 1-2 times a day, you think, "that history is fascinating, this is going to be a cool work-up." You have 1-2 patients a month that you tell your colleagues about and show x-rays, CTs, EKGs, etc, that you all oooh and aaaah over. There is some patients who are very gratifying to treat, and there are 1/4 of patients that make you want to go in the back room and throw breakable objects around.
Sometimes you drive home thinking, "I suck! how could I have not thought of that." or "Crap! Why didn't I add a d-dimer on that patient." Other times, you drive home thinking, "I managed that (airway, surgical abdomen, difficult, unusual diagnosis, critically ill patient, etc.) patient rather well. I'm the bomb!"
All I know, is that the ER is about a gazillion times better than any clinic, or the OR.
You've got to experience them all to see what I mean.