I was pretty disappointed in this.
It was really only loosely based on the anime, and that probably spoiled it for me (and a lot of others).
- The back story was hugely different. [spoiler] The basement, the "for 100 years the wall stood" - but then it turns out the virus was a couple of years ago, etc [/spoiler]
- The characters were different (I was particularly [spoiler] disappointed with Mikasa - how could you ruin her! She was incredible! And what about the leaders of the army? Where as Pixis? These guys were just creepy...[/spoiler]). Although I did like the manic brains of Hanji.
- The settings were different. [spoiler] Armin had a toy with a battery, Hanji driving a truck - where were the horses? I almost thought that the had to use a truck because these actors probably couldn't ride horses - it really is that kind of movie. [/spoiler]. I've always wondered how they managed to make their aerial maneuver gear (including refill their gas cylinders) in such a primitive environment.

It might have been better to call the movie, and the characters something different to reinforce that it is not the Attack on Titan we were expecting.

I was always a little disappointed by the anime (especially the first couple of season) - afaik, they never lived up to their potential. And then this movie. If you are familiar with Titan, this is disappointing. If you are not familiar, this will be confusing.

But I will continue to watch. AOT is a brilliant concept - just badly executed.