Death of the Author: Wanderer and Ian's love story is intended to have a message that true love is about who a person is rather than what they look like, given that Wanderer isn't even human and completely changes her body yet they still develop feelings for each other. Both the book and movie ends with Wanda getting her own body and being able to finally be with Ian, which is treated as a happy outcome. However, multiple reviewers make the point that both Wanda's old body and new body are described as attractive, which makes the relationship between Ian and Wanda seem more based off physical appearances rather than genuine love. These reviewers further point out it doesn't help that Wanda seriously considers lying to Ian that her new body is biologically 18 (the body is 17, Ian is about 25) so they don't have to wait for sex, which some readers think not only further makes the relationship seem more like infatuation/lust than love, but has some unpleasant implications.
Fandom Rivalry: With Animorphs, which also uses Puppeteer Parasite villains with a good helping of Graying Morality. Animorphs fans tend to look down on The Host as being an inferior take on the premise that is more preoccupied with romance than anything else. People who like The Host argue that beyond some superficial similarities, the stories are very different and don't have an issue with romance taking the center stage.
The ending of the book has things looking better for Wanda and the human survivors. Wanda can stay in the body of a human (who would have died without her and, unlike other hosts, is actually "gone"), the group finds more survivors, and Wanda can be with Ian while Melanie can be with Jared. That, however, loses some of its happy ending vibes when Wanda mentions that she still has feelings for Jared even outside of Melanie's body. It kind of puts a damper on her and Ian's relationship and makes it feel more like she's just settling with him.
The first meeting between Jared and Melanie. Sure, he was exhilarated to find another survivor after being alone for so long. But planting a kiss on a girl quite literally seconds after he meets her is bizarre at best and assault at worst (especially considering Melanie is much younger than him).
Growing the Beard: On the author's part. Whether you consider The Host to be better than Meyer's previous work or not, it is certainly better received.
Slow-Paced Beginning: Several reviewers have commented that the beginning is weaker than the rest of the novel.
The book has a lot of room to be really, really good, what with benevolent aliens taking over the world, the divide between what's ruled by your body and what's determined by your mind, the difference between Wanda's love for Ian (purely mind, since she doesn't have a body) and Melanie's love for Jared (more body, since her mind is overpowered by Wanda's), the morality of Utopia Justifies the Means... it could have been really awesome if it hadn't been eaten by the weak beginning and worse ending.
Cinematic Excrement considers Wanda getting the body of an attractive woman this, pointing out that the relationship between Ian and Wanda would've been more interesting if she had gotten the body of a less attractive woman or a guy instead.
What Do You Mean, It's Not for Kids?: The Host is an odd case. It was marketed as Stephenie Meyer's first adult-oriented novel, though a lot of people assumed it was Young Adult, especially because Meyer's previous, better-known series was aimed at teens (even some media outlets got confused about this, mistakenly referring to it as a YA novel) and there's no content that's particularly inappropriate for teens, either. It's worth noting that none of the main protagonists are teens: Melanie is 21 and her love interest Jared is 30, while Wanderer's love interest Ian is also in his mid 20s and Wanderer is technically centuries old. Admittedly, the main plot's combination of a love triangle and a rebellion against a tyrannical sci-fi government was a popular premise for YA fiction at the time, Wanderer ends up inhabiting the body of a 17 year old girl permanently, and then-18 year old Saoirse Ronan was cast as Melanie/Wanderer in the film adaptation, all of which may have added to the perception The Host was YA.
Critical Dissonance: The movie has been near-universally panned by critics and currently holds a meagre score of 10% on Rotten Tomatoes, with many critic reviews finding it either unbearably tedious and/or unintentionally funny. Moviegoers' reactions have been rather more mixed, with a 50% audience score on RT and 5.8/10 on IMDb. Unlike critics, most audiences don't find the movie to be a complete disaster and argue that it has its good points, though it's generally agreed it's not the most memorable film. Some audiences felt that the movie got reviewed more harshly than it deserved due to the negative association with Twilight.
Turns out having your main character be a prisoner in her own body, who spends most of the story impotently screaming at the person controlling it, is rather silly to see on film.
One of the narmiest scenes of all is a kiss scene with Melanie objecting to Wanda kissing Ian. It plays almost like Mystery Science Theater 3000.
