Okay, time to say some stuff. The general consensus on the quality of Twin Peaks over time seems to be that the first season is the best, and then it steadily declines throughout the second season, especially after Laura Palmer's killer is revealed. I agree that the first season is superior to the second, but I actually think that the show improved after they wrapped up Laura's story. It's strange that Lynch and Frost were originally planning to never (or at least not until the final episode) reveal Laura's killer, because the fact is that the mystery surrounding her doesn't have all that much story to it. It's fairly complex, sure, but enough to span a show's entire lifespan? No way. The first few episodes of the second season demonstrate how limited that plot was the most. Like, Donna meets this weird guy who knew Laura, finds out that she left a super-secret second diary with him, and then she has to figure out how to steal it? Come on, there's adding new dimensions to a story, and then there's just spinning your wheels.
Anyway, the best part of the show isn't the story at all, but the delightfully eccentric and colorful cast of characters. Almost all of them, with just a few exceptions, are great, but Kyle MacLachlan as our hero, Dale Cooper, is the best. On paper, a character like this simply shouldn't work. An inch to the left or right, and he'd either be an implausible Mary Sue or a ridiculous clown that nobody could take seriously, but through a combination of writing and acting, they hit just the right balance with him. His quirky personality makes him genuinely likable, and his virtuosity makes him genuinely admirable. And it's nice to know that a show doesn't actually need to have an angsty broody mcbroodwalking douchebag for a protagonist to be great.
Now I'm going to baw about a few characters. Nadine sucked. She was annoying and unfunny, her storyline made no sense, she took time away from better characters, and her bizarre super-strength was never once explained. Leo was also terrible. He goes from being a one-note douchebag to a one-note retard...and that's about it. The Log Lady's log had more personality than him, and arguably more acting talent than the guy who played him. Finally, Josie was a disappointment, largely because she started out being interesting, but it soon became clear that the writers had no idea what to do with her, and all the plot threads connected to her just seemed to fizzle out. I still don't know whether she was supposed to be an antagonist or a victim, and frankly, I don't think the writers do either.
tl;dr: The show was great, my nitpicks aside. If you haven't already, watch it.