I was an EMT for 3 years before applying and of course it came up on my application and inteviews. One of my interviewers specifically asked me to tell him a few call stories. After, he told me he always asks EMTs this because a lot of premeds get their certs for their applications but exaggerate the amount of clinical experience they got. As long as you are truthful, had a meaningful experience, and you can relate it to your desire to become a doctor, being an EMT is a terrific experience for your app.
One more thing, be prepared to answer "So you liked being an EMT so much, why not just become a paramedic? It's a much easier path than medicine blah blah blah..."