First thing I don't like: the Y meter. Most HN readers are nerds, and nerds like exact values (same reason I have the percentage on for my devices's battery)
Second thing I don't like, which breaks the design completely for me: my eyes have to travel a huge distance to see how many comments stories have. It makes skimming the front page much, much worse.
HN's design is about extreme conciseness. There are a few things that could be done better, but if you redesign it that has to be your #1 goal.