"The Time Merchant” is another entertaining third season classic. The Chronos character was interesting and the ramifications of going back in time and changing the past were handled fairly effectively. The episode also features John Robinson rather prominently. Since Guy Williams, supposedly the show's supposed "star", went generally underused as "Lost in Space" evolved, any episode where John Robinson has more to do is usually better as a result.
The only thing that keeps this episode from achieving elite status is the less than satisfying circumstances wherein season one of "Lost in Space" meets up with its season three counterpart. In the episode "The Reluctant Stowaway", Dr. Smith, the robot, and the personnel of Alpha Control were all portrayed in straight-arrow, deadly serious fashion. However, "Lost in Space" had changed radically since then. Because of this, by season three, even the best episodes couldn't avoid elements of silliness. Thus, the scenes back on Earth in "Time Merchant" are a little disappointing. Byron Morrow's "General Squires" is not nearly as impressive as Hal Torrey's unnamed General was in "Stowaway" was, while Hoke Howell's "Sgt. Roger" was nothing more than a Barney Fife-type goofball. Alpha Control looks a little cheesy as a result.
Also, the big change in Dr. Smith since the show debuted is painfully evident when you view his Alpha Control scenes in "Time Merchant". I wish Smith had been portrayed in less comical fashion in this episode.
Overall, "The Time Merchant" is interesting and exciting. I consider it to be one of season three's top episodes.