It's based on the James Patterson novel of the same name. I'm tempted, but then again, although Wikipedia mentions some positive reviews of the book, many of the reader reviews at Goodreads are scathing, and there are others around like this: Schlock Mercenary - Zoo by James Patterson is a Warning to Good Writers Everywhere Wondering what others are thinking. Don't want to use up good summer hours watching TV I'll regret.
I finished reading the book some weeks ago, and I quite liked it. First a reminder: Novels are fiction. Movies are fiction. TV and movies "based on novels" are double fiction. Things can happen that cannot happen like this in RL. I did not regret buying the book, I was entertained (of course, there are always parts one likes less, but this is individual taste), and what I liked best was the idea of animals fighting back. Usually when in a book the human race is threatened, it's a virus or a fantasy weapon. Extinction by organized animal armies was novel to me, and that's the main reason I liked the book. Then I googeled around a bit, and was slightly confused -sorry, haven't bookmarked where- about mainly two things. Patterson was quoted that he thinks the series will be better than the book.(!?!) Then, from the production came the message that they will be relying more on RL animals than CGI. Hopefully this was a journalistic misunderstanding, because ever since I read it, I am wondering how many poor animals will be harmed during filming.(Nowadays, I simply assume, if there's an ape in a movie, it's Andy Serkis and his crew!) All in all, the novel reminded me much of Hitchcock's Birds, and I am going to watch it when it airs in Germany.
So what does anybody think so far? Viewers seem to be voting with their feet. First episode got 8.18 million viewers (in the U.S.), the second got 7.67 million, and the third 6.56 million. The declining numbers might have to do with the beginning of the vacation season, but those are big drop offs. If viewership continues to drop that much with each episode, CBS might regret ordering all of 13 episodes for the "first season". Reviews have been mildly positive, mostly focusing on the human characters, perhaps understandably. The science, frankly, is risible. For zoo buffs, the pickings have been very limited. The only animals we've seen for anything more than a few seconds are: lions; domestic dogs; domestic cats; wolves; domestic horses; and a flock of unidentifiable (and probably computer generated) bats.
I only watched It once, against my will. The "science" was as creative and credible as that used by creationists - which is to say not at all - and I was extremely disappointed at the use of performing animals. Last but not least, the entertainment value was negligible. Simply put, it was quite the waste of time. I must note, though, that the tree full of cats was a dream come true.
I watched the first episode to see what it was like. It was a waste of time, it didn't make any scientific sense: "animals working together to exterminate humans", and was pretty lame.