I read the shit out of those when I was a kid. For books geared towards 11 year olds, they were absolutely brutal. The psychological trauma. The death. The descriptions of ripping apart and blood and asphyxiation and drownings and moral dilemma where there is no right answer....Those books were insane. KA Applegate husband wife duo wrote the early ones and left most of the rest to ghostwriters with a summary of what was to happen in them. I imagine the ghostwriters had a blast writing so much fucked up shit into a Y.A book.
Animorphs was a great concept and they went in on it hard. I couldn't believe they made a live action nickelodeon show of it. That failed spectacularly. Cheap late 90's tv cgi looked terrible and since it was a kids show on a kids channel they had to take material that was "R rated" and make it rated G. I'm surprised it made it more than season 1 and got a bit into season 2 before getting canceled.
It would probably be a lot better now, in the style of the new Percy Jackson show or something like that. We finally have the technology to pull off the effects better.