Not a good weapon when you can outrun it at a brisk jog. Moving that thing would consume like 10 galons per every 10 feet, and by the time the spinning blade comes down you would be in another zipcode.

So unlike Anime where giant machines are indestructible and fast as the speed of sound. In real life you would do more damage with a tiny drone and your target wont even know what hit him. Then you can just call it a traffic accident.