I am SUPER late to the game here, but I just finished six seasons of this show in an obsessive binge and have many thoughts and no one to share them with (since it's 2020 and they're not relevant anymore).
I really started the series because I figured I'd hardcore ship Chuck & Blair, which I did, and it was the motivating factor in my love for the show. I am so happy that they consistently wrote the two of them as soulmates through the whole series (unlike most shows where the couples will have other serious relationships and you think they might have dropped the pairing- even Pacey and Joey the first year of college seemed done for good). I was pleasantly surprised their pairing happened so quickly in season 1 and never quit from there on out. They never let you forget that Chuck & Blair had a connection, even during Raina, Dan, Louis, Eva... Plus, I loved the little touches of Chuck and Blair remembering all the tiny details about each other that showed they appreciated one another for who they were, not just for their connection ("You obviously don't know Chuck, he has a thing for roofs", "Blair, you're wearing your beret, who are we spying on?" and so on).
My main issue was that they seemed afraid to write them together, officially, and it suffered for that in that later seasons. I thought Chuck/Blair in seasons 1, 2, and 4 (return of their rivalry, hate sex leading to real sex, realizing they're still in love- I actually thought season 4 was beautiful) were fantastic, and the first half of season 5 as well, but in seasons 3, second half of 5, and 6 it was a mess. It seemed like Chuck's speech to Blair in season 2 (one of my fave scenes) about why they couldn't be together (the games will end, Chuck & Blair don't go to movies/hold hands, etc) was meta- the writers basically saying that the couple won't be the same once they're actually a couple. And I was fine with them holding off for those first two seasons, because somehow it wasn't tiring, and their chemistry and sexual tension was incredible. I expected them to do a good job of writing them together in season 3, but I actually thought season 3 was the worst writing-wise overall. I liked that they were written as functional together (pre-hotel incident), but somehow everyone's lines just seemed off. Blair all of a sudden came off a bit like a caricature with the NYU stuff, I didn't buy the hotel plot, hated that Chuck was about to rush a proposal in a hotel lobby in the finale. I just didn't enjoy the way the relationship was written... I thought maybe it was the whole transition out of high school that was hurting it, but then season 4 felt back to normal quality again.
The trajectory of the relationship felt on point until the car crash halfway through season 5 and then the writing just took such a nosedive. I didn't even hate Dan/Blair as an idea (and the two had chemistry), I just hated how they got there. Blair made a pact with God? Um, what? That's literally the best they could come up with to keep Chuck and Blair apart? Then all the bullshit about how Chuck needs to destroy his father in season 6? I even thought Blair's backing out after the Heaven & Hell ball (and after that beautiful kiss on the balcony in front of the crowd) because she wanted to be successful without him was reaching. They just kept throwing nonsensical obstacles in the way despite the fact that both Chuck and Blair at various times had been ready to put everything aside to commit- it just never could be at the same time.
While I'm glad they ended up together, the last season was a wreck (I'll detail their ending in my overall complaints about season 6 in a minute), but they were by far the most wildly enjoyable couple I've ever watched on TV and had the most insane chemistry, so the show has my love forever for giving us that. There was like a magnetic field there and every bit of emotion and body language those actors put out just nailed it.
Unfortunately, most of the cast didn't have the same type of charisma and I found most of their plots tedious. Leighton Meester and Penn Badgely (as separate entities) had the best comedic delivery out of the whole cast, so they were enjoyable to watch for that. Dan as a character though really suffered as the series went on, but I see that the majority of people overwhelmingly agree with me, so no need to detail that! I actually did like Jenny, helped by the fact that she also had my favorite style on the whole show (the goth/rocker look is my aesthetic), and she was the only actress I missed a bit after she left. Vanessa was a joyless black hole, I wish she'd been more like her book counterpart. Nate was so pretty and I will say I enjoyed him as probably the most decent person out of the bunch- his friendships (with Dan and Chuck primarily, but with the main cast of girls as well) were my favorites to watch. I never bought Blair and Serena as great friends with the amount of backstabbing and the absolute bare minimum they had in common.
Blake Lively just never had the chemistry and sparkle that the mythical Serena van der Woodsen should have had. Between her trademark mumbly delivery (she always sounded drunk) and her blank acting, I couldn't get into her character at all. She was best with Nate, but even Nate I preferred with Jenny. I can totally relate to being flighty, and I understand her character and the whole "so pretty/magnetic I never need to work for anything, can string guys along, etc etc" and even thought she sold being a sweet person despite all of that in the early seasons, but by season 5 somehow she'd just turned into a gigantic bitch. There were multiple times in the last two seasons that I just couldn't reconcile the scheming Serena was doing with who she'd been earlier on, so I guess her ending up with Dan was fitting in that sense.
Honestly, despite the weak second half of season 5 and my lack of love for season 3, I thought they'd manage to tie up season 6 nicely despite only having 10 episodes, but what the hell was that?! It was just so BORING. First, bringing Bart Bass back from the dead was not only unnecessary, it cheapened the trauma and growth that Chuck went through trying to cope when Bart initially had died. They wasted the majority of the season on filler- Stephen and Sage? Ivy? Why?- instead of working towards a satisfying ending involving the characters that actually mattered. Then, the last two episodes were a total rush job trying to get everybody in place for their conclusion. What the actual fuck was that action-movie bit with Bart Bass falling off the roof ending they did in the penultimate? Like, the music was even so cheesy that for a minute I wondered if Blair was having one of her cinematic fever dreams. Then, after spending six seasons keeping their main couple apart for increasingly unbelievable and aggravating reasons, they just marry them off in a two minute ceremony so they can't testify against each other? Come on. They totally had earned a wedding by season 6, they could have written a finale based around it in SO many better ways after spending the first 9 episodes with appropriate buildup. I even would have liked to see some of the other endgame couples develop a bit more (Georgina and Jack, for one! What a perfect match!). So yeah, this was overall a crazy enjoyable ride, but I'm still left feeling disappointed in what could have been more. Ugh.
ETA: Two minor details I forgot to mention- It drove me nuts that they never showed Chuck with his shirt off (I assume because of Ed Westwick's tattoos?). It just looked so silly when he'd lay down next to Blair, who would be wearing a silk nighty, and he'd still be in his full suit complete with socks (or worse, those long sleeve pajamas they put him in sometimes).
Also, I actually paused my TV to read one of Dan's great literary works- the story about Charlie Trout in s2 or s3- and it was just TERRIBLE. Like horribly written. So that's always added another layer to the absurdity of Dan becoming some kind of best selling author, haha.
