Well, I'm a LOT pickier about nonfiction so it's probably safer to recommend fiction.
For fiction, genre isn't as important as editing and PoV.
If it's first person point of view, chances are REALLY HIGH that I won't like it. The exceptions are if the entire thing is written as journal entries or letters, where the format is CLEARLY someone relating a story/experience to a specific audience. If it slips up and starts doing "entries" or "letters" that are really scenes, which if you stopped and looked at it you would say "no one would write that!" then forget it. But if it maintains its perspective properly, then I might consider it.
Conversely! If it's third person, limited (close or distant) or omniscient; chances are good I'll enjoy it.
If the editing has a lot of slip-ups, I'm probably not going to finish the book.
If the word-crafting is good, though, I'll probably end up rereading it several times.
This sometimes makes getting recommendations difficult, because not everyone pays attention to that. >.<
Spoiler
If you really want to do NF, though...
For non-fiction, either give me a specific translation or only give me titles in the original language; if the editing isn't the best don't even bother telling me about it, I don't care how wonderful/interesting/informative it is otherwise. If the author is giving lots of general statements make sure there's a VERY well annotated appendix or chapter endnotes... textbooks are fine if the editing was up to par, subject matter is actually irrelevant because I'll find nearly anything interesting. Autobiographies are always of more interest to me than biographies, but I'll take a biography if it's VERY well researched and without much spec-fic-style storymoding. That's all well and good IN a spec-fic work but I can't stand it in something that's supposedly non-fiction. >.< For history works, I'm better off with something written contemporaneously to the era than a "look back at X time" unless the focus is specific and narrow -like the "Engineering in the Ancient World" book was great, but "Life in the Middle Ages" I found to be rather a poor show. "Self-help" stuff is usually not of interest to me, I find them to be mostly filler. It seems like nearly every self-help book I've seen could be boiled down to maybe ONE PAGE of advice. Frustrates me. On the other hand, "how-to" books that are well done? Those I enjoy. Books on beekeeping, glassblowing, microwave repair, grafting, knots, the proper way to deal with asbestos installations, all of these have been enjoyed by me. So genre really isn't the important bit.
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A very serendipitous mistake!)
