When you are hellbanned on HN, here is what happens: nothing. And for sure you are not informed about this in any sort of way: no popup, no messages, nothing. You think everything is normal and you still can write comments, but they appear only to you, which is confusing because you assume others can see them too. You can upvote (and as usual arrow disappears) but your vote does not count. Another thing is that you are being thrown at some sort of non-cached, low-priority server that is as slow as hell. It then takes about 10-15 seconds to open any comments' page (this is confirmed by me, because once I got my account resurrected, everything start working as fast as my internet goes, same moment with no changes on my end). Another thing noticed: after your account is resurrected, your score can go up/down like before, but average score does not change (mine stays .65 for a while now). During dead period I wrote some long and, in my opinion, interesting comments, that were not displayed (especially spent some time on this one: http://news.ycombinator.com/item?id=4068798 ). A nice fellow from England noticed how silly I am for keep participating in HN community but really being a ghost. I emailed info@ couple times and told them I barely get massive downvotes and my karma stay positive for a long period of time. I don't spam or troll. Nothing happened. After couple days I start emailing PG and about 12 hours later got email from someone else apologizing about being killed and my account got resurrected.

I hope that PG/HN/team will add some features so that someone killed can know about it.

edit: sorry didnt answer: as of HN, no, the system is not that hellish. Score does not go up just for you (so you would assume everything is fine).