Read through Shingeki no Kyojin, definitely had mixed feelings on that one. It was almost painful for me to get into at all. I thought the earlier art was often terrible (it did get a bit better later on), and I had to force myself to keep reading past the first 3 or 4 chapters. I didn't find myself really caring about the characters all that much and at many points I was rooting for the Titans to kill everyone.
I made it to 42 but it prob wont be a title that I'll care enough about to check back in to see when new episodes come out.
I felt terrible each time someone got killed.
I don't get this honestly, but maybe it's just me. It's like watching some Zombie movie or show, you know people are going to be dying nonstop, and I can't really get attached to a lot of those characters. The only thing I might come back for is to look at it at a later date to see how the storyline progresses, but beyond Eren and a handful of others they're all just nameless redshirts to me, and even then I don't think I'd object to a major recurring character getting snuffed.
Maybe it's the character development, or lack thereof. A number of times I'd think to myself
"welp, there goes the one guy that looks like Eren but isn't"or
"Wait, the tiny blonde chick is a dude? What about the other tiny chick? Ymir is a chick too? WTF". Or characters would enter frame and I'd actually wonder who they were because so many look so similar, or I'd assume it was one character then find out later it was someone else. Is that Mikasa? Wait, which one is potato-girl?