It's a good episode, certainly better than the first pilot, but not quite as good as the series yet.
The negatives mostly revolve around the series still trying to define itself:
- Paul Fix is totally unremarkable as Doctor Piper, possessing neither the charm nor the ability to speak his mind that characterized Boyce and McCoy.
- Lloyd Haynes does a better job with the material, but he also has a nothing part (he doesn't even have a specific job; it's hard to believe he was an intended regular).
- Andrea Dromm is a forgettable actress in an even more forgettable role; easily the least defined of the three yeoman intended as regulars.
- The cinematography still hasn't found the bright, colorful look that would characterize the series proper, although it has more life than the first pilot, I think.
- The costumes and props haven't quite been fully realized yet, either. The phaser rifle, for example, just doesn't have the black, sleek look that would work so well for the series. It looks more like something out of Buck Rogers (or, reflecting the brief given to Reuben Klamer, the gun from The Man From U.N.C.L.E.
On the other hand:
- Shatner nails Kirk from the get-go. The writers would adjust the character of the course of the series to more closely fit his ticks, but there's a presence here that enlivens everything in a way that Hunter's more internal Captain didn't.
- Nimoy and the writers (Sam Peeples and an uncredited Roddenberry) still haven't nailed down the Spock character (that wouldn't happen until early in the first season), but the one thing they do get right is the Kirk-Spock relationship, as evidenced by the 3-D chess scene.
- Gary Lockwood and Sally Kellerman are both terrific. You immediately feel that Mitchell and Kirk have a long history, which only makes his fate more of a blow (I particularly like the moment when Mitchell loses his powers for just an instant during the final battle). Likewise, Kellerman makes you believe Dehner's temptation, but keeps enough humanity that her final sacrifice doesn't come out of left field.
- Paul Carr as Lee Kelso is also memorable (indeed, the guest stars fare better than most of the intended regulars -- alas, they all get killed off!).