My overall score is based on the last section though.
First Section [Episodes 1 - 223]
I'd call this a pretty fun anime almost out of the gate. It was really exciting seeing a very unique world, unique premise and interesting characters to wonder about right away. I really enjoyed that a lot of characters were introduced very early on as very powerful people, but we were totally left to wonder about them. This is very essential to getting people excited about what's to come.
As far as the characters go, although they are all pretty one dimensional, they are all very likeable (except for Usopp, I can't stand him). Luffy is kinda hard to hate and there is someone to like for everyone in the series.
The story definitely drags a bit. Lot's of filler and pointless sub-plots that drag on for several episodes, but still pretty enjoyable. The main plot continued to thicken and it definitely was alive enough to keep me watching.
Second Section [Episodes 223 - 516]
I'd say this is definitely the best section in the anime. This is essentially the build up to the Whitebeard arc, but not before going to Water Seven and really spicing up the story with new, powerful characters and big character development between Luffy's crewmates.
Water Seven was good, but the chapter after that was a bit dull. Kinda just waiting for what eventually became the Whitebeard arc. Once that started, I was at the edge of my seat watching it all the way through. It does go on and on and on, but you finally get to see some badass characters fight and Luffy really stepping up in power quite a bit.
Very fun watch, even though some episodes are worth skipping. I very much liked this anime up until this point.
Third Section [Episodes 516 - 677 (ongoing)]
Here is where I really started to fall off. At first it wasn't so bad, but I progressively realized that I wasn't looking forward to anything in this anime, and as soon as I caught up with the release cycle and was watching weekly since about episode 590, I realized that nothing was happening on an episode to episode basis and as it kept going, even less would happen in each episode.
The last 20 episodes has been some of the worst. Every week I watch it for whatever reason, and every week I realize that I would have missed absolutely nothing if the whole episode was turned into a recap clip.
Episodes don't really begin until about 4 minutes and 30 seconds in, and even then, it's essentially rehashing the last 5 minutes of the episode before that. They spend FAR too much screen time with reaction shots, sound effects and a bunch of shit that doesn't matter and very little with progressing the story line. I don't think there has been an episode in a while that would take more than 3-4 sentences to describe literally everything that happened.
[Overall / Story / World]
I do like the premise of the power system in One Piece. It's a pretty simple idea and pretty flexible. You obviously have to dismiss some stuff that simply don't make sense, but you fine with it... at least at the start of the story. Later on though, you quickly realize how unpolished the power system is. You have literally no balance at all. Bad guys will crazy OP powers can seemingly never exhaust their power, but Luffy is tired almost immediately after he starts a long fight. And as they add more concepts into the system, the more you think to yourself, why did we never see this before if everyone can fucking do it?
They are all traveling the grand line, but seemingly every other pirate is waiting just ahead of Luffy waiting for him to catch up. Even with a 2 year gap, pirates haven't progressed at all down the grand line while it only took Luffy 1 year to travel the first half.
The story just starts to break with time and characters are becoming progressively less interesting... However, it could be improve a lot if I didn't feel like I was wasting my time watching each episode because nothing fucking happens. (and yes, I'm including even episode 677. Doesn't justify the previous 20 being about a bunch of nothing).
