I don’t think I’ve ever really discussed how I feel about movie adaptations in general. It’s a bit of a hot button topic among book lovers, isn’t it? “The book is always better” purists and those who just don’t trust Hollywood on principle (smart move)… Me? I don’t watch films or TV much at all, so it’s a bit of a moot point. I think comic book movies work really well: it’s a visual medium being adapted into another visual medium, so it’s not quite as tricky, and actors like Robert Downey Jr and Chris Evans have done a good job at somehow embodying the larger than life characters from comics. When it’s done well, it can even bring a new cohesiveness to disparate material — I don’t follow how the fuck most of Marvel’s comics fit together most of the time, but the Cinematic Universe has allowed a lot more interlinking.
(On the other hand, maybe too much. Civil War was billed rather awkwardly as a Captain America movie when it was clearly an Avengers movie. It was about the whole team, not Cap as such. You wouldn’t get away with that in comics; a lot of people follow particular headline characters, not teams and crossovers.)
Books, on the other hand, can be a bit trickier. They’re not a visual medium, and the translation can be harder. I think some movies have done it extremely well — Lord of the Rings, but not the Hobbit, for instance — by taking pains to be as close to the source as possible. Some have been super boring because they stuck close to a book that didn’t translate well, either through narrative voice or through much of the action being in thought rather than deed. Others have benefitted by going off at a right angle (Stardust, Howl’s Moving Castle). Some have just bombed by doing that (The Seeker).
All in all, I think adaptation is an art in itself, which you have to keep in mind as well as film-making. The same goes in the opposite direction — I’m sure a very good book can be written based on a movie, but it can’t just repeat the action word for word. It’s an act of translation to a new medium, and really you need to understand the needs of both media.