Shingeki no Kyojin is probably one of the most pobular Anime series out there due to the fact that it's so easy for people new to Anime to watch. It has a simple plot and the art and the characters itself were okay, but the show had some severe issues with the story pace.
The 25 episodes which made up the first season were supposed to take 5 years but only two major events occurred which each only took a day each of those 5 years. The worst part is that those two summed up days took almost 60% of the episodes to cover. The rest covered episodes that were supposed to explain the plot better for the sake of the Anime itself.