I had never had it before, but I decided to try to make it last night. Oh wow. I'm definitely gonna make it again. Very good way to use up ground beef, and it's easy to pack a ton of veggies in there.
For the filling, I used a small cut of steak (one of my roommates told us to use it up since he went home for a week - hooray for free meat), bunch of ground beef, broccoli, cauliflower, carrots, half an onion, and a bit of tomato sauce. The top is generally made of mashed potatoes but I used mashed sweet potatoes (with an ample amount of butter of course), which worked out great. Nice mix of sweet and savory overall.
Now I have 5 servings of the pie left...plus about two pounds of ground beef in the freezer to figure out something to do with.