One Piece: It all went downhill after entering the Grandline. It tried to take itself just a bit seriously and just falls apart because that manga/show just cannot manage drama, suspense or tension at all. It's better as a silly, stupid show about a kid who doesn't know what a pirate is, wandering from island to island with no real sense of continuity.
Seriously, Ace is one of the worst character deaths I have ever seen that was meant to matter. The dude has less screen time, character, and development then a fucking duck. I honestly felt worse for the boat dying then Ace. And the best part is, he is replaced immediately by a retconned third brother, who thankfully doesn't look like a relative so the whole blood brothers thing works.
Psycho Pass: Like, what, twelve episodes in, and it goes from being a somewhat cool show with sci-fi criminology and twisting of the tech, to like a retarded 'half of the people in the city are recording themselves brutalizing killing people for shits and giggles, on day of the thing being revealed.' There are like immediately buildings burning and it's just dumb and silly.
Naruto: Uh. There are a few places, but what I can mainly think of is... after Itachi x Sasuke fight, and New Kyuubi mode, and then manifestation of ten tails. And then... Yeah, I stopped by then. Though, I found it hilarious more then bad though, as it lasted longer then both One Piece and Bleach before totally shitting itself.
Batman: Making the no killing rule. (Just a bad call) Bane breaking Batman's back. (Showing, that no, he isn't a mere mortal, he's a superhero) Limitless Resources. (Dude spends a lot of cash.) Super-Genius Intellect. (Yet he can't figure out basic things despite that dealing with criminals and the corrupt system is his forte.) Young Robin's after Tim Drake. (Seriously, 3 outta 5 Robins have died. I don't think any of them were over 15 before they bit it too.)
Dark Souls 2: Just. Fumbled everything and couldn't follow 1. Which was it's greatest enemy. Trying to continue that, when it obviously should have been it's own Souls entity, was a folly and worse for the game as a whole. Good job on making a stupid cycle system that literally makes your game moot. (At least the first has two endings, one of which forgoes the cycle.)
Breaking Bad: The show was okay up until they introduced Gus, and then they killed him off in a looney tunes esque fashion, that was also madly out of character as Gus should have just ended Walter but whatever. After that, the show just got worse and boring, really.
Persona 4: Letting your best friend casually walk away into her personal hell, then leaving and saying, "Oh the weather forecast shows it won't be foggy for two more weeks. She'll be fine."
No, you shit heads. You should do what the P3 cast did, immediately mount a fucking rescue and get them out of demonland. For fucks sake.
Metal Gear Solid 4: Well. Most of the narrative, but a few key points. 1. Accelerated Aging. Hurrdurr. 2. B&B Corps. 3. Meryl and Johnny. 4: Vamp.
Halo: Gonna hit this a bit individually. 3: Cortana spam pop ups. ***** became a virus even though shes in space a couple thousand lightyears away. Killing all the characters off except the ones who should have honestly died.
4: Master Chief being the protagonist. The stupid Forerunner dude whose only motivation is racism. The return of the elites even though we have a truth, and no, shit that happened off screen doesn't fucking matter if you can't tip your players in on it. At least in 2-3 we don't see the Elite truce made, but we see the Elites turn, and can taking the logical leap that the enemy of our enemy is a friend. Also the Arbiter is like, 'Sup, we don't kill eachother anymore. Except in multiplayer but whatever.' The 'Promethean' enemies looking nothing like the Sentinel's that have guarded every damn place we've encountered before, I mean not even remotely. 2 showed us they had some bigger tank busters, why not more forms like that? Then digitizing souls. That is dumb. Also, the manipulation of hardlight to do the impossible based on it's design. You just can't make it fold around and make copies or hold people like rope. That shit is a bridge. Just like you can't 'feel' through it, as it's light. And you're a AI. Just hijack a prosthetic hand that replicates that. But whatever i'm nitpicking.
WatchDogs: Your entire narrative was fairly poor, even if it was a better take on Batman.
Assassin's Creed: The Assassin's post 1. "Hey Ezio, the guy who can't think for himself, why don't you become the leader of the order so we can just order you to do stuff instead of having any kind of actual leadership that could stop us from being screwed over if things go bad." Connor in 3. "I will not once, ever, address actual problems facing my people, will worship the ground George Washington walks on, and kill my best friend for no actual reason." Desmond in 3. "Sure, I can trust this totally evil-not evil sentient machine thing lady."