Never seen the opposing King on the 1st rank before!!
My Coolest Checkmate

Obviously your opponent made some mistakes in the defense of his king but you did very well to take advantage of them with a rather fantastic finish.

Oh man, Bur_Oak, you are correct. I should have thought of that. Still Ke7# is a great way to end a game.

Nice finish -- the ending reminds me of this game -- one of my favourites:
http://www.chess.com/article/view/an-immortal-brilliancy
Unfortunately, Lasker also chose not to play O-O-O#.
20.0-0# would have been much more satisfying.
You say 5.dxe5 was 'almost forced' - totally disagree, I don't think I'd have played that move at all.
I have a tendency to sacrifice early and without full compensation. Something I held off for once (for a few moves at least).
Thoughts?