the very early game is awesome. Your zoning power is crazy, and your passive is just a mini nuker. as you don't have to farm and be auto attacking, your passive increases very fast. your adc may end pretty much with free farm, mostly winning it, ready to snowball the lane.
you may feel decrease of power while level 4 and 5, then you get happy ultimate, fully restoring your faith. Yes, your ultimate kills people, force flashes and stuff.

You and your adc still must not act much risky until you conclude first damage item (bloodthirster), and it may take some time. you should just def your tower and farm, stay safe buddy!

Late game you have a second ADC on the team getting kills. around 80/90% eficient comparing to main adc, since you spent mastery points on utility tab and **** on runes and stuff so yea yea. still great deal to your enemy. yay!

Fighting for adc? no problem, ashe sup is great success!
Your team have 3 ap damagers in other lanes? no problem, ashe sup gonna balance it for you!
Your team got heavy frontline, lacking damage? no problem, ashe sup will scare out your p*****y enemies!
Your adc is new to it? learning cs? no problem, your ashe sup gonna teach your b*****tches!
And more! you keep the option to change role and start farming for the good sake of the match. awesome!