Reading the first pages before trusting anybody is the whole thing. Every shop, library and store lets you do it in under two minutes.
What to look for specifically, since "does it grab me" is unreliable at that length: how long the sentences are, how much work a paragraph is asking of you, and whether you have had to reread a line. Those three predict finishing far better than the premise does, and the premise is what every recommendation is written about.