This series would probably be rated all 5 stars. Just sayin' because I love this series wholeheartedly. I'm serious. Even though, I've already said this dozens of times, I'll never stop. 
 The characters are so diverse and interesting. The world is also unique; something that I would never think of. It's really psychological when you think about it. It gets intense, especially with the anime. If you plan on watching it, I highly recommend you use Japanese dub with english subtitles to really feel the characters because their voices convey so much feeling than the english dub (in my opinion). So, Imagine going through a world everyday where there is a chance of death. Maybe that'll get you thinking. 
 "This is a cruel world...And yet...so beautiful." 
 That's one of my favorite quotes because it can be true. There are good things life and there are also bad things in life. 
 So I'm just going to point out that, I get why people dislike/get bored with the anime or manga. Some people may think, it's boring because it's just titans or something-nothing big about it. Others may think, that it's an ugly series because of the titans. 
 For those answers, I got something for you, too: 
 -It's not just about titans, it's about life in a world where you can lose hope. Except with characters trying to deal with it. 
 -If you think it's ugly, read another pretty manga 
 ---5 Stars!!!---