I also thought this was a great listen. Season 2 - not so much. I feel like they really dove too far into the back-and-forth between the founders and I personally find it much less interesting.
Before PJ Vogt and Alex Goldman did Reply All, they did TL;DR. It was pretty much the same thing but over on WNYC. There's plenty of great episodes worth going back to:
http://www.onthemedia.org/tags/tldr_podcast/
http://gimletmedia.com/show/reply-all/