Lately bad CGI effects have crushed my suspension of disbelief by taking me fully out of the moment. It's a powerful tool and allows you to show audiences things that they might not otherwise ever see and, for the record, I love CGI work. However, it seems that it's become increasingly easier for directors to get lazy and dump everything on CGI work. The problem with CGI is the very fact that it can make things nobody has ever seen before. If you show your audience one or two big "Whoa, what the HELL?" moments that wouldn't be possible in the real world, they'll suspend disbelief and go with it if you do your work right. If you make your film a huge string of impossible moments where physics just doesn't exist in the world, people will be off the boat by the time Legolas Mario-hops his way up the crumbling stone blocks.