I think it depends on what part of the sphere grid you send him to. On my most recent playthrough of FFX, I sent him to Rikku's path, and having an additional character able to use Steal/Use (but mainly Use, for Al Bhed potions) was a great addition. I always have Yuna nip onto Rikku's path just for Steal, Use and a handful of HP up spheres on her way, so that way I have 3 characters able to use Al Bhed potions.
Next, I'll add the additional Stength Up sphere from beating the Goers onto Rikku's path, so both she and Kimahri can benefit from the boost early on. Kimahri's early high stength stat, coupled with the sharp boost in HP and agility from Rikku's path makes him quite deadly until about halfway in the game, when everyone else comes in to their own.
I do fully agree with a lot of what has already been said in this topic though. Blue magic should have been used a lot better, of Kimahri should have had a full path of his own, instead of suffering from an identity crisis after 6 hours of gameplay!
Next, I'll add the additional Stength Up sphere from beating the Goers onto Rikku's path, so both she and Kimahri can benefit from the boost early on. Kimahri's early high stength stat, coupled with the sharp boost in HP and agility from Rikku's path makes him quite deadly until about halfway in the game, when everyone else comes in to their own.
I do fully agree with a lot of what has already been said in this topic though. Blue magic should have been used a lot better, of Kimahri should have had a full path of his own, instead of suffering from an identity crisis after 6 hours of gameplay!