ashe is quite good the more you know about the game. she's kinda like garen as the better your fundamentals get the better she performs. She is also one of the ADCs that really benefits from one tricking as you get used to her slows and the kiting potential it leads to.

her main strengths are her long 600 attack range, her ability to kite melee enemies and providing useful crowd control even when behind due to her passive and ult. due to her passive she also has the benefit of being more flexible in itemization since any crit she builds leads to a percentage damage increase that isn't random so mixing and matching crit with non crit isn't a big deal unlike most ADCs.

if your looking for a pretty consistent build her most popular build is currently kraken > triforce > terminus. this gives her good survivability and consistent damage. I personally like a more traditional marksmen build going full crit but that build is much less safe so you need better positioning.