Xenocide, from the ender series. Enders game was good. Speaker was OK I guess. Ender was a whiny bitch the entire time but the descolada mystery was interesting. Now that's solved and he's still a whiny bitch and then he just solves basically every single problem with his super ai that can do magical space/time bullshit. The worst deus ex machina I have ever laid eyes on. I physically threw the book across the room at one point. I hate leaving books unfinished, so I slogged through the rest at like 5 pages per sitting, rolling my eyes out of my head the whole time.
Anything with Ender after the first book is terrible. But the series that sticks with the happenings on earth after Enders Game is pretty good. I especially like the book that has Bean from a child through battle school.
I have to rank Children of the Mind as one of the just plain weirdest books I've ever read. Just when I thought it couldn't get weirder, Orson Scott Card manages to throw something else at you. After I finished Children of the Mind, I decided at that point I was going to move onto some other book series.
I'll still recommend Ender's Game as that's a classic, but I wouldn't bother with the sequels.