Part two of "Time's Arrow" is a competent but unremarkable conclusion to the competent but unremarkable part one. If part one felt anemic as cliffhangers go, then at least part two didn't have a high bar to clear to live up to its predecessor. And that's pretty much what it does: lives up to part one without for a minute transcending it.
The procedural aspects of the plot here are dealt with fairly reasonably and not without a certain level of basic interest. We get the entire crew back in the 19th century (posing as a traveling acting troupe) where they try to figure out the nature of the time-traveling alien soul-eaters, who are sucking the life energy out of human beings and then leaving their corpses behind where their deaths would be chalked up as cholera victims. Meanwhile, Picard meets Guinan for the first time in one of those paradoxes that proves Guinan's dialogue in part one correct: Picard meets Guinan in the 19th century, where she does not know him; much later (from her perspective), she will meet him again in the 24th century, where he will not know her.
Alas, the time-traveling alien soul-eaters turn out to be one of the most perfunctory alien devices in quite a while. There's exactly one scene where Picard attempts to communicate with them, and their single-minded determination to continue feeding on human energy from the past is not open to negotiation. But the scene doesn't even make them menacing but instead just sort of ... there. And that's that. In the 24th century, they're ultimately destroyed with a torpedo blast from orbit. As time-bending alien mysteries go, this one proves surprisingly pointless. Meanwhile, the significance surrounding the discovery of Data's head plays out here as a necessity of closing a logical loop (and there is some fun to be had with that), but with none of the consequence that was implied in part one about Data's possible mortality. His body is taken back to the 24th century where Geordi reunites it with the 500-year-aged head.
The bellhop (Michael Aron) turns out to be Jack London, in one of those conceits that acts like it's a Major Reveal but instead comes across as a ho-hum writer's lark that doesn't have any real point. And probably the biggest problem here is the continued presence of Samuel Clemens (Jerry Hardin), who ends up getting transported to the 24th century along with much of the rest of the Enterprise crew, where he provides a (mostly wrong-headed) running commentary on the future. Hardin's portrayal is so endlessly cartoonish and overplayed as to make Clemens an annoying presence throughout.
If I sound like I hated "Time's Arrow," that's not really the case. On balance, it's a watchable time-travel storyline that might've worked if trimmed down to a single hour featuring a lot less of Clemens. And I enjoyed the last shot of Data's head being left in the tunnel, to be uncovered 500 years later. But this doesn't add up to a whole lot more than a collection of scenes, some clever, others not.