That's the first thing DS16 and I said when we started reading it. We read ALL 70+ (counting all the "extras") of the Animorphs books back when they were big. Very similar, except in the Host, most people evidently just "disappear" rather than stay there trapped in their brain. Which seems worse to me.
The first time I read the Host all I could think of was how much better the Animorphs series was. But when I reread the Host a few times it really is a different story. The "host" really seems to be much more of a human type soul, whereas the Yeerks seemed to be more evil - wanting to take over and destroy humans rather than feeling bad about it. Read it carefully or plan to reread it to enjoy it more!