Personally, this was the first generation where I loved the games but absolutely hated the accompanying anime saga.
This series attempted to be a reboot by reverting Ash back into a noob and not showing strategy in battle, to doing even the most questionable decisions it even made his companions feel like he was doing a strategy they knew wasn't right.
It got especially bad around the Nimbasa Gym where Ash planned to defeat Elesa with just his Palpitoad. It did easily defeat her Zebstrika, but got taken out by her second Pokemon, Emolga. Ash didn't expect Palpitoad to fall so early, he had to run out of the Gym mid-match just to get his second and third team members - which ended up being Snivy and Pikachu. Snivy fell to Emolga as well, leaving Pikachu to take it out and face Elesa's final Pokemon alone. Said final Pokemon for Elesa was Tynamo, which I view as a complete joke since it only gets four weak moves until it evolves yet somehow she trained hers to be a speed demon and put up a real challenge to Pikachu.
And then there's the resident Ash companions - Iris and Cilan. I found Cilan okay to deal with since he does have his comedy moments, but Iris was definitely a different story to me. She basically acted like a bully to Ash, with her signature "what a kid" remarks, making her feel like she's superior to Ash without even knowing a lot about his previous adventures. I am heavily against bullying (I have autism, which made me prone to being picked on) and having a so-called "friend" of Ash be so mean to him like that was definitely promoting the wrong message to the target audience. That's why Iris is my most hated Ash companion to date.
Then there was Ash's Unova team - a YouTuber named HDvee recently declared it was Ash's worst regional team, and he does have a good point. The Unova team had barely any evolutions and most of the team members that did evolve barely got screentime, mostly being shoved aside in favour of the trio that was Snivy, Pignite and Oshawott.
And finally, there's that controversial result at the Unova League against Cameron, a total noob who only brought in five Pokemon into a 6v6 match, and even thought the league was taking place in Johto. Ash did get an early start on Cameron but then that jerk's Riolu evolves into Lucario and destroys Ash. Seeing a trainer like Cameron beat Ash, and you have yourself one of the worst writing ever regarding a Pokemon league. The Kalos league result was known for splitting the fanbase, but Sinnoh and Unova was when leagues really showed the writing staff and their controversial decisions.
And finally, this series ends with a pointless filler arc known as Decolore Islands. Don't even bother with it.
Basically, in a nutshell, if you hate dorky Ash, controversial writing decisions, bad team handling and horribly written companions in general, I recommend avoiding the BW series altogether.