I myself have been catching Northern Pike on a fly for years. I still find it amazing when people are surprised that I am catching 40" plus fish on a fly rod. Whatever.
Jake Forsline has put together a nice video on just how much fun this fish are on a fly rod. If you haven't target Northerns yet on a fly rod then grab your 8wt, some wire leader material and some long "meaty" flies and go get you some. The take are some of the best of any species. Well worth the time to get one on the hook.