We might have crossed paths at some point - I worked for a private ambulance in Tamworth/Madison, as well as volunteered for Bartlett-Jackson, and spent 2 days working for Tinker!
At least when I worked there, you did your 911 calls, but after those, you worked in the ED. If the trucks didn't roll all day, you still kept working in the ED. So, you have to be a medic who doesn't mind having your "downtime" taken up with patient care stuff. You're wiping buts or giving meds, not checking up on Twitter while posting.
You also need to really be a team player. You are working right along side the nurses, relying on each other, supporting each other. So, if you're a medic who dwells on the "Nurses always be, like,..." kind of petty sparring, you wouldn't like the collaborative approach at the Friz.
You also might feel like you aren't quite as independent as you have been at other jobs. You're working alongside your med control all day long, and both they and the nurses (quite rightly) will be supervising/directing you all day long. (OTOH, the RNs always gave the medics wide latitude in areas in our domain. Code stuff, etc.)
Also, if you were concerned that you weren't super-lifesaver-medic-man before, working in the ED will be a bit of a disappointment. There are plenty of butts to wipe, patients to help to the bathroom, Foley catheters to be placed, sutures to be removed. Your scope is fairly wide (I pushed tPA a few time there), but your daily duties are pretty unremarkable, and don't require a gold patch. SO you have to be cool with that.
Oh, and also, the union guys down the road always made more cash than us. You have to be a medic who thinks the trade-off of less-$$$ vs cooler job is worth it!