You may view this as a vast improvement over the dreaded original series episode "Spock's Brain" or even a variation on Next Generation's own "A Matter of Time," but not quite the genius of Voyager's "Living History" (but better than "Think Tank") or as fun as Deep Space Nine's "In the Cards." Bottom line, though, "The Most Toys" won't disappoint you.
If you like the character of Data, it's absolutely essential, in ways you probably wouldn't imagine without having seen it.
Simply put, this is an episode where a main character is "collected." Data is in fact one of the "toys" in the title. As distinguished from the very different case of Starfleet wanting to collect him in the second season classic "The Measure of a Man," everyone's favorite Star Trek android is deemed a valuable curiosity. That in itself would probably make for an interesting story. But the episode delves deeper.
Data doesn't end up worrying about himself. He becomes far more concerned about his kidnapper's assistant, who ends up realizing how little she means to the collector even though she's served under him for years. It's Data's shocking act at the end of the episode that speaks to how much of an impact this experience has on him. I won't spoil it here in case you haven't seen the episode, but rest assured it's a defining moment for the character, one that far elevates "The Most Toys" beyond its sometimes routine story beats (it's also another franchise example of a main character apparently being dead and the rest of the cast trying to prove how that couldn't be the case; DS9's "Armageddon Game" has the best example of that particular Star Trek trope).
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Memory Alpha summary