The Haruhi series teases a shitton of stuff but very rarely gets into the meat of the very batshit insane stuff, which can be a turn off for many.

Katanagatari can be very wordy and if you aren't prepared for something like it you can find it incredibly boring or badly paced.

Aria can be very slow for many because it is a pretty strong representation of "nothing happens" in a plot progression sense. There is almost no plot of any kind so anyone expecting even a semblance of one will be sorely uninterested.

Death Parade has issues of hamming some things up when it could have taken a more calm approach to some of the games (like it did once I believe).

Space Battleship Yamato 2199's last two episodes feel tacked on and unnecessary.