I pretty sure its spoiler free ; ) I saw the manga after the movie but the movie is not that accurate to the manga. The manga had many interesting characters, different types of safe guards. Then realize that the movie is an hour half long so it's difficult to cram all the characters in the movie. The first 20 min I thought the setting of the situation is similar to No Game No Life, the story was very different. The CGI on the movie was no that difficult to adapt from the regular anime. I like how the safe guards looks terrifying, gives themovie more horror type of taste.

The movie doesn't explain specific details about how the machine became dependent from the humans, and the lack of detail makes you create your own imagination, and that's the part of the reason that I like BLAME!.