Welcome back! I had the benefit of marathon-ing the entire series for the past 2 months and finally made it in the nick of time (literally watched the finale of season 3 just over an hour ago) to watch the premiere of season 4. What a great and wonderful ride! Thank you Mad Men for making it all worthwhile with a fresh, new, engaging episode that made me love this show all over again.
To give too many highlights would probably give away too much in the spoiler department, so I will just say it was intriguing to see where the characters have ended up in the aftermath of season 3. There is obviously a long way to go for all of them, and it's going to be difficult but they seem up to the challenges.