High mobility and speed of movement are two best traits of Bangalore. She is not very good at sniping or tactical maneuvering, but when you need to attack quickly, then she's the real deal.
Bangalore also can throw a canister of smoke that prevents other players from seeing her, which is excellent for escaping or stealth attacking. However, if you're playing against Bloodhound, this trick won't work as this legend can see right through it. So in this regard she is rather vulnerable.