Tobar said:
It's not strictly necessary but episode 19 leads directly into AoU.
I thought that was very cool how you can edit the last scene of that episode (with Coulson's very last line) with the very first shot of Age of Ultron.
I have enjoyed all of season 2 of AoS, but I just wish that they would have had chosen a better actress for the role of Skye's mother.