The show revolves around 4 members of "the gang", Mac, Dennis, Charlie, and Dennis' twin sister Dee. During season two, Frank Reynolds, Dee and Dennis' father is introduced, which made the show complete. (Had Frank been there from the beginning I'd give this show a perfect 10)
It's not like there's necessarily plot arcs in the show per se, but there is continuity and things that'll pop up randomly and also recurring characters like The Waitress and Rickety Cricket.
When you watch from the beginning, it's funny how this show makes you care about the characters and their bonds with each other even though they often betray, manipulate, and even often inflict physical and mental pain on each other throughout the course of the series, to each one's personal benefit. But this is a dark comedy so if you're looking for deep character development and meaningful epiphanies in your comedy..look elsewhere.
It's definitely an acquired taste, but if you're into seeing what normal sitcoms don't show, Always Sunny is for you.
Even halfway through it's 7th season, IASIP continues to deliver strong plots for it's characters with great acting. Props to Rob Mchelleny, Charlie Day and Glenn Howerton. Also Kailtin Olson and Danny Devito are amazing in their roles, continue the great work, guys. Can't wait for seasons 8, 9 & hopefully more!
"How do you catch a cricket? With a Giant bird!"