For anyone not caught up with Arrow, please consider refraining from reading the following as spoilers will be included. Please keep in mind this article is based purely on my personal opinion and nothing more.
While Arrow has been a show that I used to love watching, in recent seasons, it has quickly become a show that I do not enjoy as much as I want to and that comes from various issues, beginning with reusing plots.
Reusing plots
The beauty of both season 1 and 2 of Arrow is that the story was intriguing, the characters allowed the audience to invest into them and care for them, and the villains weren't predictable a lot of the time. While season 3 wasn't amazing, the story was still better than season 4 but that's not saying much. However, what made season 1 and 2 so good was that they had stories that pulled people in because it wasn't predictable, Unfortunately, by season 3 and onward, the show really fell and that was primarily due to to reusing plots. For example, Oliver being accused of being Green Arrow has occurred on the show five times, if not more. This is honestly laughable and quite frankly it becomes boring, but the biggest issue is that the audience no longer feel a sense of threat when Oliver gets accused or arrested because by the end of the episode, he'd be clear. Season 6 followed the same trend with Oliver being accused by the FBI of being GA, only this time they're making it a primary plot for the season. Another example of the writers reusing plots is the amount of times the villains have wanted to destroy Star/Starling City. This is unbelievable and just mind-numbing. Merlyn created a device to destroy the Glades, and that made sense because he wanted to clean the city of criminals. Deathstroke wanted to destroy it because he wanted to personally hurt Oliver. However, Ra's Al Ghul just didn't make sense. I mean he wanted to destroy Star City because Oliver was the new Ra's and it's tradition for a new Ra's to get rid of his hometown...? What if Oliver was from New York City or Chicago? How the hell would Ra's plan on destroying such large-scale cities? Damien Darhk was basically the same as Merlyn except he became mental later with wanting to cleanse the entire world and not just Star City. Prometheus was really good, and I'll give credit where it's due because his motivations were different and he was really interesting.
However, if Arrow continues to reuse plots constantly then it will be losing a lot of its fan-base which is truly a shame as the show started out so good.
The drama
In any show, or movie out there drama exists and that's perfectly fine. You literally cannot have a story without drama, otherwise what's the point? In saying that, there should always be a limit to the drama in any story.
Now season 1 of Arrow used drama to an advantage, for example, Arrow utilized the theme of family and the drama revolving around that theme. Whether it was the Lance family, Merlyn or the most obvious, the Queen family, they were all interesting in their own respects. Season 1 and 2 both highlighted the significance of the mother/son relationship between Oliver and Moira and just how much it develops. This was GOOD drama! I loved it because it didn't rely on cheap dramatic moments, and the story didn't rely on romance. The story was full of depth and had many interesting moments that pulled the audience in.
Nevertheless, this doesn't last. Late season 3 of Arrow really was a low-point for the show, especially as the show begun focusing too much on "Olicity". Now, this wasn't a huge issue until late season 3 which then followed on the entire show. The biggest problem was that the chemistry between these two was being forced down and it just didn't seem genuine. Felicity quickly transitioned from a character that was loved in the first two seasons, to becoming someone utterly annoying. The show even swayed from being about Green Arrow, and begun focusing too much on the romantic relationship which isn't ideal for a show that's categorized under action-superhero.
Lack of realism
After Arrow begun using supernatural elements and magic, the realism quickly drained away from the show. Now, the usage of magic, meta-humans and supernatural elements on Arrow just didn't work, and while it works on The Flash, Arrow is supposed to be a grounded show. Arrow set out a dark, gritty, realistic nature which worked wonderfully in both season 1 and 2, and part of that is because of how threatening it felt. When we watched Arrow, the stakes felt high, and when characters died, they would remain dead. However, after season 2, this changed and with that change came the lack of quality on Arrow.
When Oliver Queen was impaled in season 3 by Ra's Al Ghul only to basically be thrown off the cliff of a mountain, I didn't believe he would remain dead and that was because of the introduction of the Lazarus pit. However, the writers really didn't try here, they didn't even try to explain how Oliver comes back, which is weird considering the Lazarus pit was part of the story in season 3. When Thea Queen "died" in season 3, I thought this could be something great, mainly because it divulged into how dangerous the world of Arrow is. Nonetheless, when she was brought back by the Lazarus pit, the show begun disclosing that feeling of intensity. Bringing in the element of magic in season 4 just did not fit whatsoever on the show, I get they wanted to try something different and I like that they had the courage to do that but they could've done it in a way that would've worked. Damien Darhk was too OP for Oliver due to his magic and it frustrated a lot of viewers to constantly see Oliver losing his fights when just a few months ago he had defeated and killed Ra's Al Ghul.
Team Arrow
Season 1 and 2 offered the best of Team Arrow, consisting only of Diggle and Felicity. Season 3 introduced Roy Harper as a permanent member and that was a good choice especially with how they developed his character from season 1. The reason we loved Diggle and Felicity being on Team Arrow is because the writers allowed them to be on the team for a long period of time before introducing new members. This gave the writers time to develop Diggle and Felicity as individual characters but also their connection to Oliver, and in doing so it allowed the audience to start caring for them. The writers done something similar with Roy in season 2, they made him an outside help to Team Arrow, however by the end of season 2 we see that he becomes part of Team Arrow. What I liked is that they didn't just let Roy in, he really needed to prove himself to Oliver which makes sense because you don't just simply let anyone into a team like this. What annoys me though is season 4 made Laurel Lance a permanent member of the team, and while I loved her character, she was obviously not yet fit. It boggles me that Oliver continued to let her out with him when she constantly got beat up and was basically incompetent. Thea joining made sense because by season 3, she had been training with Merlyn and then continues to train with Oliver in season 4. Season 5 wasn't any better in this regard with Curtis somehow being allowed out in the field because he felt "helpless". The rest of the recruits joining in season 5 didn't really make much sense either because Oliver kind of just let them in without them needing to prove themselves to him in the same way that Roy did. The fact that writers kept changing up Team Arrow leaves little time for characters to develop and allow us to like them. Now, the development of Wild-dog and Dinah Lance made the characters better but Team Arrow doesn't feel as genuine as it did in season 1-3.
The changing tone
My last point is the massive issue of the writers attempting to constantly change the tone of the show. The inconsistency in changing tones messed with the fluency of the shows and story. Season 4 was basically tackling a lighter tone than that of previous seasons but the problem is, it wasn't convincing. You can't simply go from three seasons being something to then completely changing in just a season. Season 1-3 were gritty and the story was dark which was fine honestly, but you can't change the tone of a show so suddenly. You have to invest time and slowly progress the lighter tone into the show, otherwise it'll just feel odd and messy which was the case for season 4 of Arrow.
Even then, Arrow returns to the dark tone in season 5 and again changing the tone from one season to another. It just felt inconsistent and anyone that followed season 4 knew it wasn't much lighter but if they're going for a different tone then develop it and stick to it. It seems they've learnt from their mistake as season 6 is following the dark tone, while having found a balance of dark and light.