I was really looking for new cards using exile mechanic and I'm not disappointed with this one. It's cheap, fast, just one XP, so great value there and can be returned to deck with Déjà Vu for free for next scenario.
Just fail all skill tests, get value out of them (for example using "Look what I found!", Oops!, don't care about fails when Drawing Thin used) and still have 3 more actions (assuming all actions required skill tests).
It can be played for another investigator without location restriction which sounds a bit broken and can be life saving if someone failed miserably skill tests when fighting Elite enemy.
Lifeline can be even more beneficial for Stella Clark - in the most extreme scenario, she's failing 3 skill tests, then fails extra action's skill test coming from her signature ability to finally get 4 extra actions from Lifeline.
The only thing you have to care about when playing this card is to make sure your actions require skill tests and the fail effects are not too harsh.