I'd read the VN. I've done both, but I'm very glad I chose the VN first, since there are a couple big changes in the anime I was unhappy with. To answer your previous question without spoilers, there are decisions every now and then that make you branch onto another route that leads to an ending rather quickly, where picking the other option will make the story continue. The true ending can be a little tricky to get, I had to follow a guide after my first time through so I could get it without messing up a bunch.