Unlike some people I not only read the tags of the novel before picking it up but have even read all available chapters. The overall content was very enjoyable to go through though I realise it won't be for everyone; especially since each chapter if a rather big time sink. However you can hardly blame an author for enjoying what they do and such long chapters definitely have people that enjoy them.
I am one of those people, evidently.
There are some small errors that I noticed such as one battle having 150 fallen angels, 50 of them being killed, then some more all accumulating in there being only 200 fallen angels... It can be a bit annoying but I'm sure anyone reasonable will understand that it's not exactly game breaking. Just something funny to tease about as, funnily enough, the author (I hope) is only human so will make some dumb mistakes.
There are some elements I'm not all there for, like it does get annoying the 200th time he says "I'm not a hero but an idiot", yet it improves as time goes on. Also goes on about immortality being a curse since you watch all your loved ones die... When most the people in DxD are eternally young.
All in all if you like Highschool DxD you'll likely have no issues overlooking those details and those who don't won't understand them.
Recommend as long as you have the time to sit down & read.