Will something change in Kaneki this season 2? Does it even matter?

If you're talking about the change in his hair color, it does matter. It signifies that he's less selfless, and if you've seen his inner conversation with Rize, you'd know it also signifies how he'll value himself and accept that he is a ghoul who must eat humans/ghouls to survive.

This also opens up a darker storyline....

Season two-also known as Root A-doesn't have as much action as the first season does, but it's still very important. Without saying any spoilers, Tokyo Ghoul Root A is what people are looking for after the cliffhanger the creators left in the first season. Don't bạn want to know what happens after Kaneki changes? Don't bạn want to find out what happens to Ayato and how Anteiku will deal with the CCG and Aogiri? Tokyo Ghoul Root A is very important, probably even a bit thêm than the first season is, it is a definite yes to watch Root A, if bạn want to keep up.