When 'Lost' was in its prime, it was must-watch television. Remember first watching it, found it remarkably easy to get into, was hooked from the start and was on Season 3 by the end of one week. The general consensus is that the final season is a disappointment and cannot disagree.
It is very difficult following on from two tension-filled show high-points in "The Other 48 Days" and "Collision" and be as good, but "What Kate Did", while not as great as those two, accomplishes this very well. It is by quite some way one of the best Kate-centric episodes (don't dislike her as much as some do but there are far stronger characters on 'Lost'), and does see her at her most interesting in quite some time.
The flashback, no matter how pretty clichéd it is, gives one more of an insight into Kate's past and answers the long unanswered question of why Kate was a fugitive. The mystery itself is handled well though the whole black horse stuff leading up to the reveal for my tastes was a touch on the silly side. It also is successful in allowing us to sympathise with Kate's situation despite her un-condonable actions.
Having said that, the island events and mysteries are more compelling and advance the story and characters much more. Particularly the bond between Locke and Eko, which is mysterious and thought-provoking (Eko really intrigues as a character, and is every bit as intriguingly acted), the shocking cliff-hanger and with Sawyer, where his pain and anguish is very believable as is the mental instability dialogue. Hurley's line about Bernard is very funny.
"What Kate Did" benefits from great acting. Terry O'Quinn can do no wrong and Josh Holloway's Sawyer is fantastic. Evangeline Lily continues to grow vastly as Kate and having an episode centred around her may have induced some groans and worries but it does allow Lily to stretch her acting abilities and she does in a very emotionally committed performance.
A great job is done with the writing and development of the characters thanks to a taut, smart, passionate and complex script that has a lot happening while not feeling over-stuffed.
On a visual level, "What Kate Did" is beautifully photographed, as always making the most of the island setting. The music is as always chilling and understated and some of the show's best direction is present here.
In summation, an excellent episode that progresses everything beautifully and makes Kate the most interesting she'd been on 'Lost' up to this point. 9/10 Bethany Cox