It has nose mounted cannon firepower, is a steady gun platform, good views, and as has been pointed, can dive and retain energy. It doesn't turn as well as it should but can still out-turn a lot.
Widewing has pointed out on numerous occasions that this bird has a light wingloading that would seem to indicate it should be turning better than it does in game, and that war-time tests bear this out, showing it to have a turning capacity similar to that of an FM2. Like the Pony, the Ki-61 seems to have a bug in the modeling somewhere. I predict that if this ever fixed the Ki-61 will become quite the nice ride and maybe even popular.