The short answer is YES, Kubotan works very effectively for street self defense.
Kubotan is being used frequently by a police officers as the basic non-lethal weapon taught enforcement academies and if such professionals use it for such critical situations that means that it works.
Basic self-defense skills with a Kubotan can be taught in an hour or so. A full course can be completed in a day. But it requires some practice to develop the required the motor skills after taking the course.
In law enforcement jobs, Kubotan is often used to get people out of close-quarters situations. They’re great for extracting people from vehicles or from doorways or other areas where they grab on to a fixed object and hold on to resist arrest.
In grasping a fixed object like a steering wheel or a door frame, the subject exposes their wrist, which is the primary point of attack with the Kubotan in an arrest situation. In a crowded environment like a bar, a Kubotan was much more useful than a traditional impact weapon like a baton or an aerosol spray.
The great thing about the Kubotan is that You can carry it just about everywhere, and they aren’t expensive. Most people don’t know how to use them, so if you lose control of the Kubotan, it’s not likely to be used against you the way a knife, gun, or pepper spray could.
I think it’s an excellent choice as a personal defense weapon. It’s best to get some training from a qualified instructor. If you locate an instructor, ask some questions about where their training came from and what organizations support or endorse it.
Get yourself a Kubotan if it is allowed in your city and carry it in your keychain, find a good instructor to give you the basics of how to use it and just practice that regularly, you never know when you might need to use it.