Insane. It’s very easy to trigger her reaction 2 times in a turn, and to succeed by a lot besides.
Winifred’s biggest drawback is that it can be difficult to find tests to over-succeed with. In a group setting she therefore excels in a similar role to Finn, by engaging that one most problematic enemy and keeping them occupied Wini can turn a poorly located enemy into a repeatable source of cards such that evasion isn’t as big a sink of actions as it might be for other characters. In a solo setting Wini needs Lockpicks up right away so that she can reasonably commit her Opportunists to a number of tests without losing them. The end result of this is a draw machine that rivals even Minh.
Of the Mono-color investigators she is quite easily the best, with access to a card pool which complements her strengths, but she does struggle with Willpower tests. For this you will probably want to hold onto a couple guts and maintain a healthy respect for which tests you can fail without major problem.
Take her for a spin, you won’t regret it.