I've never played the Ninja Warriors arcade game, but I read that it wasn't all that impressive. The SNES version seems to be a remake and it's one of my favorite beat'em ups. Mainly because the game doesn't adhere to a lot of the usual beat'em up conventions. For example, this is one of the few 2D beat'em ups where you can block attacks, including bullets! Also, unlike a lot of beat'em ups, you can perform a powerful crowd clearing attack without using your health bar, as long as your power bar at the bottom of the screen is full. This adds a bit of strategy as it is sometimes best to not rush forward when you can wait a few seconds for your power bar to fill up
The action also takes place on a single plane where you can only move left and right. This means that the action is more in your face since you can't get away from your enemies as easily as in other 2D beat'em ups where you can move in all directions. Lastly, rather than give you a teeny, tiny health bar and expect you to burn through extra lives like other beat'em ups do, this game gives you only one life. The cool thing is though, that you get a very long health bar. This actually makes sense since your character is a cyborg and can absorb a lot of punishment. Basically, if you've got the skill, the game gives you enough health to get through each stage without need of extra lives.
I also like some of the interesting moves in the game. For example, Kunoichi can do a jumping attack that allows her to bounce back and forth between two enemies while doing damage. You can also pick up and throw objects that no normal human would be able to pick up, being that you're a cyborg. It's cool how you can destroy some of the game's background objects too by throwing people into them. Another cool feature is that you can do a very high jump to avoid getting surrounded or to get yourself out of a tricky situations in addition to a standard height jump for just regular attacks. You also have powered up special attacks that use a portion of your power bar and each character has two or three grab attacks, crouching attacks, dash attacks and powerful combo finishers that are great for knocking down multiple enemies. It's a decent selection of moves and all three character have completely unique play styles in addition to the usual speed and range differences that every other beat'em up has.
Top all that off with decent graphics(the three main characters have cool character designs) and a pretty solid soundtrack that sounds similar to Wild Guns and you have a perfect beat'em up in my opinion. The game also has a pretty cool surprise ending too. One of my all time faves in the beat'em up genre and extremely underrated. Play the japanese version if you can, as the female enemies were changed in true Final Fight fashion for the US release. Though both US and Japanese versions of this game seem hard to find in my experience. There's always emulation I suppose. Here's some gameplay footage from the japanese version featuring my favorite character Kunoichi:
and one of my favorite tracks from the game's soundtrack