SNK is a terrible anime
It's utterly the same thing as SAO, the anime is not good.
It's cliche, it rips off of several series
Plotlines are forced into far too fast: Story began and "took off" the first episode. This is the main problem with the anime of today, especially shounen. Nearly no explanations for anything, just "WHOA EPIC SHIFTS" and "EPIC BATTLES" to keep the casual watcher entertained enough to fanboy. Nothing is necessarily "clear", random plot-twists out of nowhere and with the atmosphere it gives off, generic villains.
Very cliche main character, terrible supports: Main characters personality is an average joe, supports are nothing more. No one was a unique personality in even the slightest. It's like you are watching/reading a series called Bland, amirite? Not even eren's random temper gives him a personality. And you can't change a character that hasn't been even remotely developed yet, as the SNK "writers" think so. Eren's power up was the most cliche, predictable thing I have ever witnessed.
Predictable story: Comes off as a typical shounen. Eren's mom was killed by a titan, he wants to kill titans, joins military force he looked up to, deuteragonist follows along with him and so does the supporting character, emotions are had, training begins, emotions emotions, more characters are met, etc. No redeeming qualities about the story. It's not unique, it's not interesting, it has all been done before.
Terrible fanbase: Probably the worst thing about this series. The Fanbase is full of wankers who think it is a masterpiece and the best anime ever made, and that it is so deep and strong, they are absolutely delusional and do not actually evaluate the series. Anyone who doesn't like it doesn't know what "true anime" is in their eyes, as I have heard by such wankers of the series before.
Usually it's just got into by new-comers to anime, or those who have only seen generic Shounen like Bleach, Naruto, Death Note, etc. It's NOT good.