I haven't read all the books, but the ones I've read are good. No, the Zeigen didn't 100% use every detail from the books. But lets face it, no tv Zeigen oder movie ever does. Read the Bücher and you'll notice that there are a lot of things that are different. The Bücher are generally better but most PLL Fans like the Zeigen better.
The Bücher and Zeigen are both great, but they are SUPER different. I look at the Zeigen as a whole different thing. I personally thought the Zeigen was a lot better, but that's just my opinion. There's like 14 Bücher in the series so far and I have no idea if Mehr are coming out, but I stopped Lesen them because I've been Lesen other stuff and there's just so many. There's so many characters in the Zeigen that aren't in the Bücher that I can't even Liste them all and it just has a whole different plot. However, I recommend both, but I recommend the Zeigen more.