I played Mark Harrigan fairly extensively this weekend, I wanted to share a few thoughts that maybe didn't occur to me at first blush, particularly when related to the new cards (no spoilers expect for player cards).
Let Me Handle This: this is still pretty solid. I don't know if I'm gushing over it as much as when I first saw it. It's useful. It has a spot in my deck for now. There have been games where its been *extremely* handy, but there have also been games where it has sat in my hand and done nothing. It's hit or miss.
True Grit: I've heard some people on the forums being rather down on this card. I think it's great, I don't understand the reluctance to use it. It provides 3 extra hp for no XP cost, which is nice, and being able to soak for other investigators is also extremely useful. I especially like this in Mark Harrigan, because he wants to be using his character HP for Sophie, True Grit gives him a card to place damage on when he does suffer it during the course of the game. No slot occupied either, that's fantastic.
Ever Vigilant: I didn't see myself using this much but I put it in a deck and gave it a try. I'm much more impressed than I thought I would be. It can be tricky to use because of the hand limit, and you want to draw it early obviously... but when it does work it is a real boost to your tempo, and it's a steal at only 1 XP. Can be annoying to run up against the hand limit though, but worth it if you run a lot of assets.
Finally, Mark himself: I really like him. I think he's my new favorite guardian. Free card draw from time to time is very nice, Sophie helps him do anything he might otherwise have trouble in. His sanity/willpower is weak, but that can be built around. He pairs pretty well with Daisy (the best Intelligence and the best Combat: I mean who knew?). Daisy was running Strange Solution (Restorative Agent) which is a huge help to Mark.
Mark can be phenomenal at dropping bosses, specifically with the Shotgun. Because Shotgun damage is based on how much you succeed by, Mark is far and away the best shotgun user we have. With his base combat of 5 and +2 from Sophie, mark is easily at 10 combat before he even commits cards or resources. 5 damage hits are easy to achieve. Vicious Blow or The Home Front can increase it further.
A shame we don't have many useful Tactic cards. Like just about everybody else, I run 2 Shortcut (which is great). Nothing else seems to be worth it.