I went EDP and was thrilled with the results. The entire process flew along quickly, and I got my answer within 24 hours of my interview. However, I have spoken to a couple of people from other schools who said that they weren't notified in a timely way, and it interfered with the submission of their other applications. You need to ask to speak to some of the med students from the school you are applying to, and find out if the school was responsible or not with their ED people.
On the bright side, just as you agree to attend if accepted, they agree to notify you by a certain date. If they don't, you can call them to find out the status of your application. Also, you could go ahead and submit applications to other schools (once the EDP notification deadline is past).
This deadline is often in early October. A little late, but not so late in the game that you won't get an interview (unless your application was no good anyway).
One thing that wasn't mentioned earlier is that some schools also have additional criteria that must be met. For some it is merely in-state residence. My school also had minimum 30 MCAT and 3.6 gpa to apply EDP, in addition to the residency requirement.