Biggest Anime Disappointment?

For me, my biggest appointment of all time was Attack on Titan. I didn't watch it until much later, with all the hype and the mainstream success and all the cosplays I've seen and repaired at cons relating to Attack on Titan, and the constant hearing of "Mikasa is my Waifu" led me to watching the series to review it on my YouTube channel. So, when I decide I want to review an anime, I always watch it at least twice, exception being very long series (such as Fullmetal Alchemist Brotherhood). Of all the ones I've watched multiple times, the only one I EVER dreaded, was Attack on Titan. I ended up realizing that a lot of the main characters are a lot of poorly executed tropes (because really, there's no such thing is not following any tropes anymore, only whether a trope is well-executed or not). Eren is that initiall weak protagonist who's driven but somewhat useless who conveniently gets stronger as the series progresses. Armin is like an apparently smart Slippy Toad who monologues WAAAAAY too much. Mikasa is a bad*ss but one-dimensional character who clings a little too tightly to Eren. Heck, the best characters didn't get much screen time, in the anime or the OVA (Sasha and Hanji). BAH! I'm getting too into it. Despite its flaws, I did see Attack on Titan as a solid ridiculous-spectacle-style series (it's not got the greatest of stories, but it's not terrible), I was just disappointed because I felt it just didn't live up to all the hype.

Also no game no life so that actually would depend on if a second season is made or not. If a second season is made and then it's a perfectly acceptable ending, if not then the last 15 to 30 seconds kind of screws up the ending.

@MadokaMimi I feel your pain and I'm with you there, I'm or less seen a lot of the easily available anime that's finished, not watching online that is, and now i end up researching anime series before i decide to start it to avoid either terribly unsatisfying endings or more likely and more often an unfinished ending we're there because is new or just never received another season. It can be a pain in really limit when I can view but i would rather have that instead of watching something that ends up without a ending.

Biggest Anime Disappointment was Gantz, I say this because it was one of those read after watching animes. Honestly if they came out with a second season or even rebooted the series to give it a proper ended i would be delighted. As it stands now its a let down.

It seems that almost all of the disappointing anime shows mentioned on here have bad endings. Just underlines the importance having a satisfying resolution to a story.

Sword Art Online,do I really have to explain?and Tokyo Ghoul but luckily the manga saved it. Had pacing issues and the marketing or whatever focused way too much on the gore and action when to me is not the point of the series is has a lot more going for it in the manga.Alot anime adaptions are lackluster from their source material nowdays.

Too much hate for SAO. It really wasn't that bad. Someone on here mentioned Fooly Cooly, sadly the manga was pretty much the same ending.