J.R., J.R., deceit is his hobby,
He's always up for a scam.
J.R., J.R., he'll stick it to Bobby,
Maybe he'll sleep with Pam.
J.R., J.R., he's truly a Ewing,
Doing harm near and far.
You'll be destroyed if you get him annoyed,
So try to avoid J.R.
I really hadn't watched Dallas when it was on, though I found, when I watched some of the episodes, that I was nonetheless familiar with most of the essential points: J.R.'s scheming, Cliff's wussiness, Pam's bug-eyed fits, Bobby's terrifying hair. These are things that are so much a part of the pop-culture consciousness that we can't help being aware of them, at least on a subconscious level; it's like people who have never watched Friends can probably still describe it fairly accurately.
Nobody needs me to describe the pros of Dallas (J.R., the backstabbing, the over-the-top emotion, the sheer fun) and the cons (cheesy dialogue, cheesy plots, Victoria Principal's acting, Patrick Duffy's hair). The one thing I have to say is that, after watching some episodes, it occurs to me that Dallas not only revived the prime-time soap, it might have helped to change the prime-time drama.
For most of the '50s, '60s and '70s, TV dramas consisted entirely of self-contained episodes, with no overlap from one to the next. This was partly something the networks insisted on, not wanting characters to change too much and not wanting people to be confused if they were tuning in for the first time. But it was also an aesthetic thing: the gold standard of TV drama was considered to be the anthology show, with self-contained stories, and the lowest of the low was the lowly soap opera, with stories that continued on and on. The makers of prime-time TV drama aspired to be more like anthology shows than soaps, and that meant avoiding "soapiness," including any attempt to carry over a storyline into subsequent episodes.
Dallas started out with more or less self-contained stories, and got soapier as the years went on. But it was never as much a pure soap opera as previous prime-time soaps. Peyton Place was a soap opera, through and through: the episodes didn't even have titles, and they consisted of a bunch of scenes advancing separate storylines that would never end. Dallas was more a hybrid of drama and soap: each episode had its own overall story that would be more or less resolved within the hour (J.R. hatches some scheme. Flip a coin whether this is "J.R. succeeds" week or "J.R. gets his comeuppance" week), but strung through that story would be soap-style ongoing story points that would be continued and developed in future episodes. That basic format was picked up by many of the "arc" dramas that arrived in the '80s and '90s, shows like Hill Street Blues and St. Elsewhere and The Sopranos and Buffy: soap-style story arcs strung through a series of self-contained episodes. What had once been scorned as too soapy -- and there were other reasons for scorning the arc format; some TV veterans felt taht the story-arc format gave the showrunner too much power to set stories, and froze out freelance contributors, and I think they may have had a point -- bacame the preferred format for the TV show with high-art aspirations. Did that start with the gleefully low-art Dallas? I don't know, but it would be interesting to look more closely into that.
*I should give props to the episode of King of the Hill where a character sings his own parody version: "J.R., J.R., he's a really bad guy/Who lives on a ranch with his mom."