If you do not know nor seen either of Devilman and Cyborg 009, then you should look up the source material since this crossover will only give you a short introduction.
Not to mention that this crossover is special as it both series are hardly owned by the same company or person. The few things they do share is their message of war and that their authors where buddies and some times assistans on different projects.
This, unlike the OVA, is more serious toned and has less fun with the characters. Storywise, this has a more direct conflict between each side and is a much shorter than
The art is decent. The most details goes to the background and it does look good. However some of the character look stiff and has many square shapes. It look like they where drawn natrualy. But that my opinion.
The character act as they should do, but there is hardly any interaction with each part which makes this crossover forgettable.
Mikki in general. There is not enough action for both parties. When they do fight, it's over too quickly.
The crossover lacks stuff to make it worth while. It seems that the author is setting up for something big that is not presented in this manga, and I'm not talking about the OVA since they feel unrelated. This is a middle of the road manga. So if you have read either Cyborg 009 or Devilman, then this one might be so that you can get more manga entries on your list, since this is not obligatory to read. You are better off watching the OVA.