Ashe , is the most easy adc to play with she has a perma slow that dont let any enemys run away , she has a stun , she has everything also she's married with trynda *_* , but what can i say about her is , if you are used to play league you will know how to play her :)

She's really good, with her utility .

But quite frankly, Ezreal/Corki/Graves are the top AD Carries right now. But a well played Ashe can put a bad Ez/Corki/Graves in their place. And her ult wins games.
Her first hit crits are great, her ult is great. She can kite for days.

The problem is her mobility during a team fight. There are so many tanky gap closers being picked every game that it will give her a problem. As long as she is protected, her slows can dominate.

Pair her up with taric and play safe and shes a fine choice.

Ashe isn't op nor under powered.... she has the same amount of tools as other adc's... just different ones.... Ashe has no ad or attack speed boost or escape or gap closer and that's why shes over looked.... but she has a lot of cc and map awareness and can still do pretty insane damage after u get some main items.... via IE BT PD

last hitting. What you should do is to move around erratically around the creeps (this prevents Ashe from auto attacking the closest thing), and only stop to move in to "last hit" a creep when it is one hit away from dying. Let your creeps take them down, and then deal the killing blow. I also do not recommend using Volley on creeps as it pushes your lane past the river, making you more vulnerable to ganks as you are further away from your tower.

You should engage with you ulti but allways be behind your support and jungler