When we're learning Torah, when these thoughts come up it obviously means we aren't focusing on our learning. If something doesn't really appeal to you it is most likely that it is in fact really important for you to learn, and yet in order to reach the sweetness of this sefer, you simply need to get through the bitterness, the peel, just like with most fruit.
After all, who put this sefer in front of you? Who orchestrated the entire situation in which you now find yourself asking this question? HaShem.
There are two schools of Torah learning, the school that says learning should be entirely for its own sake, and the school that says learning should be in order to connect to HaShem.
According to the Torah entirely for its own sake school, what could be better than a sefer you feel entirely detached from? Voila! a perfect opportunity to learn purely for the sake of learning, after all you already know you don't want to learn this sefer.
According to the school of learning in order to connect to HaShem, does the sefer limit HaShem? Maybe you should learn something else that makes you feel closer to HaShem, but do you honestly think you can't connect to HaShem through the sefer currently in front of you? Also the Baal Shem Tov teaches that sometimes HaShem hides himself in two levels of hiddeness such that He is hidden and we don't even know that He's hidden. So, there's a chance another sefer might make you feel closer to HaShem, but you might not even know how hidden He actually is. With the book in front of you, you know for sure He's hidden -- voila! only one level of hiddenness, He's now that much easier to find, guaranteed.
There are occasional reasons to stop learning particular sefarim, but they are pretty extreme: 1. If a sefer is making you depressed, stop learning it for a while. 2. If a sefer is inflating your ego it's a good sign you aren't ready for it. 3. If a sefer is making you think about things you shouldn't be thinking about, you have to work on yourself first. 4. If a sefer is actively otherwise interfering with your avodat HaShem, you should look into it. In all these cases you need to get help from a Rav/Rebbe who can guide you. It is almost always possible to overcome these challenges with the right help from a Rav/Rebbe but sometimes the dangers aren't worth the returns. (ie. if a sefer is making you depressed, that's really dangerous, likewise if it's encouraging your ego.)
In short, barring those extreme circumstances, it's important to give a sefer another chance. The first step is to remind yourself why it is you are learning Torah at all, then what your goal is, (ie. connecting to HaShem) then whether you have really been true to your goals vis a vis the sefer in question.
As the Baal Shem Tov taught, HaShem creates the walls in order for you to prove you really want to get to Him. (Randy Pausch in his 'Last Lecture' said something similar but a couple hundred years later.) The Maor Einayim actually drove the point home when he explained that a sefer is just a collection of letters, when you sit down and open the sefer, HaShem puts the wisdom into the letters, forming words, sentences, ideas etc. In other words, the letters in the book are a conduit to the Wisdom which HaShem constantly places (and re-places anew each moment) in the Torah.
If you aren't overpowered by the words on the page in front of you, then take another look and focus a little more. They can and will move you, if you make room for HaShem and let them do so.