I can fill in on some of these

-- Forbidden Island man I'm loving the app. I sort of stopped playing the board game because I have so many other co-ops that I consider slightly better (though I still like FI, it's just very simple) but the app is great. It helps that there are achievements and I dunno the game is actually tougher than I remember it strangely.
Elder Signs I've only played the Android version but I liked it -- if the iOS version has achievements then I might get it -- certainly when the expansions come out. People should know the art and theme are awesome but it's a very lightweight almost Yahtzee-like game (still fun though, much better than Food Fight).