Pros:
Massive Amounts of damage all game
Great mobility
Great escape
Great 1v1 capability
Decent push with Ravenous Hydra
Lane ganks almost always end in a kill

Cons:
Squishy as hell
No CC
Not much AOE

Kha'Zix is a very unique champion because when you get his ultimate ability you are able to change one of his other abilities to make it better. When you hit level 6 and take a point in your ultimate, you can either evolve Taste Their Fear (Q) or Leap (E). You want to evolve you Leap if you want higher mobility or you can evolve Taste Their Fear (Q) to do higher damage. I personally evolve my Taste Their Fear so I can snowball early. Next i'll evolve my Leap, then Void Assault (R). The reason I evolve Void Assault is that after using it, it procs Unseen Threat(passive) because the other team will not be able to see you anymore. It also procs the Sheen passive on trinity force when used, so with evolving Void Assault, you will be able to put out massive amounts of damage.

Farming on Kha'zix is fairly decent, just last hit with q and w just don't spam so much that you lose all your mana.

For your jungle, you want to start at your blue, then get the white creep camp. After that I ward the enemy red and take their golems while I wait for them to get to their red. Once they are at their red, I let them kill it, then I kill them depending on what champ they are playing. Normally when they finish their red they will be low enough to one or 2 shot, giving you first blood, their red buff, and their blue buff. Then lane ganks will be easier and it will put the enemy jungle behind. If the enemy jungler isnt squishy enough, get your blue, get your white, then get your red. By then you will be lvl 3 unless your teammates gave a bad leash.

Kha'Zix is a great champion to use to carry your teams in order to earn ladder points. His high damage without having alot of kills makes him great for solo queue. He also has alot of outplay potential with his leap and his ultimate.