Yeah, the only way to really beat kira for sure in a sword fight with his shikai is to either be so much faster that he cant keep up or having so much power that it doesnt effect you very much, to where it just puts more weight into your attacks. So he is really strong in sword fights, and good at kido, and seems to be decently fast, plus he is smart. He is pretty much the ideal vice-captain right now..

He would make a pretty decent captain if he had a good bankai and more reiatsu and speed... just saying.

Although, he does have a really bad weaknesses.. as in, if you dont use a sword, but say ice, fire, ash, etc to fight your sword fights, hes at an extreme disadvantage.. I guess you call them kido-based zans? Those who have zanpakutohs like ichigo or ikkaku become are at a disadvantage against kira.. Although those two might actually be strong enough to mess kira up in a fight with just brute force.. Although he does have kido.. but yeah, talking sword fighting here...