All three movies are weirdly related between each other, same as with the Rainbows movie that is related to the original series but in a weird way, although, beyond that all the stories seem somehow (?) unrelated (?)?
If you're expecting some sort of sequel of anything, you will be extremely confused, if you're not expecting anything at all you'll still be extremely confused. I totally forgot that the 3rd movie was already out for a few years and decided to watch it today, I might rewatch all of them soon.
So, to finish up, you won't be disappointed but you won't be marveled by these movies either, but still will make you think about what Bones intended with these movies which, I hope, they decide to make a more concise development of their ideas without going too Evangelion or Rahxephon on it.