Are you guys kidding? Richie was the best. The actor does an amazing job at playing a tough, just-outta-jail gangster with a hard-on for the world 24/7. His fashion sense... late 70s early 80s... same clothes he had before the can, almost everything he wore was like a size too small for him.
He's stuck in a time loop and has a massive sense of entitlement (he'd have been next as boss if Jackie was alive) not to mention he never backs down from Tony.

I found his death to be anti-climatic... but it was necessary to show what kind of sick "who-oar" Janice really was.

EDIT: Exactly. Richie also reminds me a lot of people I know. Plus his expressions and mannerisms, it doesn't get any funnier! Like when Paulie and Silvio visit him about the ramp or his attitude when the guys throw him a homecoming party.