First I'll start with submissions: all to often Hacker News looks like any run of the mill news site. No longer is it the spot I rely on to go and see what the hackers are up to. Because too often now it's the same junk on Digg.
Comments: the quality of comments on here is pitiful. They're used to be good discussions and relatively long, well thought and written comments. Again, like Digg it's getting where people are just doing a 1 line/sentence post where seems like they're just trying to hit on something that other people will vote up for more karma points.
One line posts can sometimes be better than rambling on and one. If you get straight to the point a pithy statement can be more rewarding. However, there is definitely a problem with snarky one line put downs as the guidelines suggest.