It was a fun and entertaining anime. The pacing was good, didn't drag on anywhere, the action was good too.
The premise of the anime is cool and interesting with all the demon world stuff and going against Satan etc etc. Although the story telling is cliched but because of good execution, it is still enjoyable to watch.
Most of the characters are your usual action anime characters, like the hero having lots of guts, not so much brains and great potential inside. But there were some interesting ones too, but sadly they didn't get that much screen time or closure.
I did feel that the many of the supporting characters were not that interesting, even if they did get some closure time.
P.S Blue flames are really COOL.