It's almost the same as the old sytem except you never lose unread icons unless you do as suggested and use the "mark forums read". You can also use the "mark topics read" in individual forums which will just mark all the threads read in that forum. There's benefits and drawbacks to this system. The benefit is you will never lose unread threads, for example if you're reading the forum and get interupted and come back in a half an hour they are still marked. In the old sytem they would have been all marked read.
You can also just use the link for "view new posts" instead of looking through individual forums. This is by far the easiest way to navigate the forums.