Hello, I'm Maorre and this is my Riven guide. She is one of me three favorite and most played champions along with Fizz and Lee Sin. I usually play Riven as a toplaner but I also like to play her mid and she also works fine in the jungle, although I will focus mostly at lane Riven in this guide.

Pros
[*] Very good AD scalings
[*] Fast wave clearing when maxing Q.
[*] Good mobility
[*] Very good at taking down squishies
[*] Doesn't use mana
[*] She can dash through smaller obstacles like Cataclysm and Crystallize
[*] Ki Burst AoE stun

Cons
[*] Her Q and E can't go through walls like a flash
[*] Very cooldown dependent (that's why I usually go Ionian Boots of Lucidity unless they have really hard CC or magic damage)
[*] Shut down so hard by someone who builds a ton of armor
[*] Also shut down hard by a silence (that's why Garen is impossible to lane against with her since he will not just silence with Decisive Strike all the time but also buy a lot of armor]]

http://www.mobafire.com/league-of-legends/rune-page-planner

These are my runes for Riven, if you're not going to face early magic damage you can go x9 Greater Mark of Scaling Magic Resist instead of Greater Mark of Magic Resist.

I usually max Broken Wings for maximum damage output and best farming ability. Maxing Ki Burst is also viable, but I prefer Broken Wings