I've been using the D5200 for about a month now. I absolutely love it. Actually, I was torn between getting a "normal" HD video cam, or going to what I had considered was the "Dark side" (DSLR). After talking with a fellow Videographer, he told me that he never regretted getting his Nikon.
And now, neither have I. It's also my first HD camera, I love the quality of capture that comes with the unit (my previous main gear is a Canon GL2).
Congrats on the purchase. I know that you will definitely enjoy your new camera.