Most readers have two responses to narratives that they read: There is an initial, more emotionally charged response, and then there is the reflective response that involves a review of what led to the original response.
Certainly, the response should include reflection upon Shelley's view toward science. As the infamous Charles Manson told the media when people villified him after the Sharon Tate murders, "You made me what I am." (Manson was a product of the prison systems having been in jail most of his life; he had also asked to not be released when it was time for him to be paroled, but he was set free.) Certainly, Victor Frankenstein created the creature, and, repulsed, he abandoned his new creation. Does this abandonment justify the creatures actions? Has Frankenstein "made" him as Manson asserted that he was formed by society and his jailors?
These are the questions that you will have to answer. Refer to incidents and passages in the text for your support as well as the attitude of the Romantic author who is suspicious of the benefits of science.
In Shelley's Frankenstein, two central issues are nature vs. nurture and the irresponsibility of science. The reader is, most likely, supposed to understand that Victor's lack of nurturing and his practicing irresponsible science, lead to the monster's committing of atrocities. And the atrocities come back on Victor, of course; they affect him directly--they ruin his life. This emphasizes the atrocities and shows the direct result of Victor's behaviors.
A reader's reaction should somewhat follow these lines of thought. One cannot help feeling sympathy for the monster's situation, but at the same time being horrified by his actions. That's part of the point of the novel.
Your personal reaction is, however, subjective. I cannot write about your personal reaction. You might, for instance, feel strongly about the monster's desire to learn, and your reaction reflects that. On the other hand, you might have a brother the same age as the boy the monster kills, and react strongly to that. Maybe you're a mystery buff, and you really like the unravelling of evidence against the monster concerning the boy's death, and that's what interests you. Or maybe you don't like the somewhat sappy, idealistic portrayal of Victor's perfect marriage, and you secretly think the wife gets what she deserves--after all, it is just fiction.
In other words, your reaction is what it is, and no one can really describe that but you.
I know that there has been much discussion of this over enotes. It is a significant part of the novel. In the end, I guess I feel that while what the monster did was reprehensible and cannot be condoned, I have to place much of the blame at Victor's feet. This is what I experienced hearing about the monster's actions, his development of self consciousness, as well as the understanding of his needs. The monster never asked to be brought into the world, never asked to be invented. The monster sought guidance and nurturing from Victor and he abdicated his responsibility. If you want to call it "parental," that could apply. Victor ran away, literally, when the monster approached him and sought his care. In the end, this becomes the lasting legacy I had with the reading about the monster. He is an abandoned child, and Victor, a deadbeat dad.