As we can read in the intro of our tourtour:
Islam Stack Exchange is a question and answer site for experts in Islam, students of knowledge, and those interested in Islam on an academic level. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every question about Islam on an academic level.
Questions about the opinion of Muslims on a book about Islam can be on-topic, as this could lead to an academic kind of discussion.
But on the other hand there's always the risk that such a question would be considered as opinion based, as for Example ibn Kathir is a well known and accepted scholar among sunni Muslims and his tafsir is one of the major sources even if it is well known to include so called israeliyat (doubtful stories which have been taken from Jewish (or other non-Muslim) sources). Therefore his tafsir includes also a lot of disputable stories.
Now when it comes to a biography or a book about an Islamic topic written by a non-Muslim you should know that many Muslims (and Scholars) would take them with much prudence if not refuse them at all. There are only a few accepted (not by all Muslims) non-Muslim authors and not a few of them are reverts.
And you should avoid a question about book comparison as this is clearly off-topic and hardly fit the SE model, even if there's a new proposal about software comparison on in Area51.