A very loose adaptation, with maybe a few key elements pulled from the original storyline, this version of Crisis matches in name only.
This isn't the worst storyline, but some major liberties were taken that totally changed most of the critical and shocking and memorable plot devices of the original story.
My biggest gripe with this version is it did not do justice for the entity that is the Anti-Monitor. In this storyline, you could argue it was not even a sentient being, and instead just a reflex to a multiverse that needed a natural balance.
The Anti-Monitor from The original stories had a mythology that was deeply tied to the Green Lantern Corps and the creation of the multiverse. It was an anti being that was evil and calculating, and was the catalyst for the excitement and pivotal battles to save the multiverse.
It baffles me that in a medium like animation, that does not have the limitations of live action, the Crisis story was not followed much more faithfully. There is a reason that crisis is still talked about today, 40 years after it published, and that is because the storytelling was so well paced and spanned from interpersonal to intergalactic.
I'm sorry to say, but DC needs to take a page out of Marvel's comic playbook, and give the fans the source material, and stop attempting to improve upon it.