Unlike Mangas, when you're reading a LN you have to use your imaginations to make those visuals in your head. You have all these wow fantasy and super cool scenes and perfect transitions made up because there's nothing else to go on except for a couple of illustrations. LNs generally also have cramped far more details than mangas in a single volume, and people want MOST if not ALL of that to be shown.
So when an adaptation turns out different then what you have imagined, it can be slightly disappointing. The better of us learn to curb our expectations and allow for some leeway, the worst of us don't.
But lets be realistic- DxD builds it's foundation off sexy girls, there is no artistic high ground here. Saying that it's a masterpiece or that it's now ruined doesn't really hold much water.
The main issue apparently season 1 and 2 for DxD were remarkably faithful to the LN, but due to event circumstances between two particular novels being interconnected, the current season is adapting three volumes into a one-cour season, rather than the usual two volumes in a season, so those said two connected volumes would work for season 4 of the anime. So some things need to be rearranged. However the final product is, the LN's author has already said he's satisfied with the adaptation.
The LN readers on AS? They're coming unglued about how the season is ruined--one of them started in as early as episode 1, after spending pretty much all of the last anime season shitting on the currently-airing series and hailing DxD as a masterpiece. 'cept now he's shitting on it too. Pretty much every episode thread has been littered with complaints from these people, and I and others are getting tired of it. We've already had a mod come in and tell them to use the comparison thread, because these spoiled LN reader brats keep making unmarked spoilers about it in their rage.
So, to me, it's becoming the ZnT forum all over again. What is it about light novels that poisons the readers so?
Unfortunately it seems to be the case whenever any one series become super popular enough. You'll have an influx of... Low quality readers. I still hang around Index to occasionally answer questions and wrangle in some off topics, but the majority of the discussions and 'speculations' I bow out.... Well, also because I'm not up to date yet so there's nothing I could say.
I don't know the exact situation with DxD, I didn't even know about the Anime until 30 seconds ago, but of you're not too attached to the series just do "hit-and-run" posts to get your feeling off your chest each episode.
If you want to stay and fight, well that's more tricky...
The only regulars in the ZnT forum were the translators, and they despised the anime because of how far it deviated from the source material. And they hated it when anyone else expressed an enjoyment of said anime, especially if they hadn't read and acknowledged the superiority of the LN.
It was pretty bad, especially as the reputation system was still in effect while the show was airing. You couldn't fucking post any good review of an episode without getting at least one neg-rep telling you what an idiot you were. If you made a remark about a detail of a show that didn't quite match up to what they read, they assumed you were also a translator until you clarified--I said that Saito's jacket didn't look like a parka, and I was asked what translation dictionary I used, as they immediately assumed I was referring to the translation of the term.
It was fucking miserable, and I couldn't complete the anime's third season for months because of all the negativity stemming from those translators, and only completed the final season long after it had finished airing. It's pretty bad when part of me feels vindicated that with the author's death, those guys don't get the conclusion to their LN, while anime viewers at least got some form of closure thanks to season 4.
Bllaaahhhh. LN readers in the High School DxD forums are trying to turn the place into a 2.0 version of the Zero no Tsukaima forum.
It's these attitudes that make it so damn difficult for me to get back to reading the LN versions of a franchise, like TAMNI. Nearly all of my encounters with people who read LNs have just been so... god damn poisonous.