Did you go to
https://www.behindthename.com/bb2/ ? From there you can select one of the boards and it should look quite a bit different than it does when using
https://www.behindthename.com/bb/
If you mean that v2 doesn't look noticeably different than v2 did previously, then you are correct. The default theme has not changed much. You can however change to the "classic" theme by going to the Help page (
https://www.behindthename.com/bb2/all/help ), scrolling down to the Settings, and toggling the theme.