Despite having decent rating on both MAL and IMDb, majority of the anime community disliked it for their own reasons. However, I still recommend that you watch Guilty Crown. There are some episodes that have ups and downs and to be honest the first episodes are quite stale, it's lacks something to get people hyped and get hooked to the show. But eventually as the story progresses the show leads to show reality via subtle messages. Keep an eye out for those. Although some episodes are quite boring to watch, you should at least finish the anime. The plot was kind of all over the place. SPOILER ALERT: The ending reminded me that not all people are the same and that they would sacrifice themselves for the greater good of the people and that sometimes they will choose decisions based on what's going to save the person/s that are most important to them, family, friends, lovers and etc.
Animation would be 8/10 there are some rough parts, recommendation 6/10 and the OST would be 10/10 and I highly recommend you to take the lyrics to heart. That's just my opinion.