After re-reading volumes 1-6 before moving onto the final volumes of Welcome to the NHK, I finally managed to finish reading the manga just now. My feelings are fairly mixed: I did enjoy my read but, at the same time, I was left thinking that there was waaaaaay too much padding forced in--far more than in the anime. Because of all the needless content, my enjoyment dropped considerably after the first two excellent volumes. If only for the fantastic art I can't score it lower than 7/10, though.
Volume eight was by far the most disappointing in the entire series. It all felt so pointless and, in comparison to the earlier volumes, it was far less entertaining. There was lots of chatter yet I never found myself caring about what was being said, or even following most of it. The story ultimately never went anywhere in the end; instead going in circles as Misaki pushed forward with her love contract, Satou went along with it because he had nothing else and Yamazaki rambled incomprehensibly about starting a revolution. All I saw were the difficult to follow conversations of not-so-sane people that were shoved in to extend the story to 40 chapters.
Whilst I am still covering the negatives, I will also add that I was not best pleased with how the original story was changed in the manga. There were lots of small (but important) alterations that were made; some of which seemed to have been made as the manga was on-going. A good n example is how Satou first said he was not a virgin (in the novel and anime he slept with his senpai whilst still at school) and then later said he was. The most bothersome change was how Misaki only lied about having a bad childhood in the manga: it made her already difficult to like character outright dislikeable... for no reason. Too many silly changes were made in order to extend the length of a fairly short story.
On the flipside, I did like the first two chapters of volume seven quite a lot. The events that took place in those chapters never occurred in either the novel or anime, and they were only able to work so well because Satou was still a virgin in the manga. Kashiwa's easily my favourite character in NHK, and the 'so near yet so far' romance between Satou and her is the most emotional part of the story for me. So, a few chapters that gave the pair more time together were very welcome additions. It was nice to see Satou confess his feelings in this version... even if he later went back on what he said because he did not have what it would have required for him to take his relationship with her forward. Life truly does suck.
In general, I do not like how open-ended every aspect of the NHK story is left, but I have still always found the relationship between Satou and Kashiwa moving. I actually came close to crying during episode 14 of the anime simply because, even. The reader/viewer fully understands why Satou doesn't do what his heart tells him to, yet it is hard to watch when you know the two could have been happy together. If only he had had the balls to put his arm around her when he was not a recluse and she was not married now--his future might have turned out slightly happier. What makes the whole situation agonising is the fact that Satou is a better match for her than her the guy she ended up marrying...
...Anyway, to sum it up, my thoughts are that, although still very good, the manga is definitely the weakest of the three versions of NHK's story. It has some nice additions but the majority of the new content does not actually add anything. We did not need to see Satou spend time at his parents, coming up with masturbation plans whilst he was supposed to be finding work, and we also didn't need to see him spend time wondering around homeless. The novel was a bit too short, the anime got the length just right and the manga dragged on for too long. I certainly do not feel bad about spending over £40 on the manga but I do feel I should have spent the money the anime instead. OH WELL!