Most of Riot's game-centric teams consider Yorick a "toxic" champion. He has a fairly "brain-dead" style of play where you, effectively, spam ghouls, which have a slow, attack reset and life steal component to them. Also, his ult, created literally at the final hour, used to crash games with Mordekaiser. Yorick crashing Ascension mode was just the most recent example of this.
Generally, Riot personnel have the opinion of either distain or outright hatred for the champion (Morello once said that Yorick's release was "Riot's biggest mistake.") Even current Riot staff, like ZenontheStoic, says "f*** everything about Yorick" when you bring up the champion in conversation.
Currently, Yorick is very hard to bully out of lane, but he's not necessarily going to win you a lane, either. Start with your W, then prioritize R>E>Q>W as you level up.
Generally, there are two ways to build Yorick, depending on how the game is going, but I usually start with Manamune and Sheen, along with Merc Treads. You can then go Frozen Heart or Iceborn Gauntlet and Spirit Visage for defense or Trinity Force for offense.
Your ult, which creates a duplicate for 10 seconds unless the target dies, which then resurrects that champion for 10 seconds. It's usually best cast on your team's hard carry, either AD or AP, as said ally would likely be the other team's target.
Finally, Yorick's getting a full rework... Soon™. We don't know when it will be released, how much the rework will change or keep of the Gravedigger or anything meaningful about the rework except that ChampUp "just started working on it."