Generally speaking, I don't mind Christensen either. I think that much of the darker scenes of ROTS, and the murder of the Tuskens showcase that, with the right material, Christensen can deliver a solid performance.I hated Jar Jar. He was offensive and annoying, and I never got the 'joke'. The Phantom Menace went off the rails for me as soon as he showed up. I got nothing against Ahmed Best, but Jar Jar was a misguided attempt at humor or to sell toys or something, to appeal to kids I guess.
I also didn't like Jake Lloyd for Anakin, but I don't blame him or his limited performance. I blame Lucas for that. Despite my dislike of Lloyd's performance overall I do think he did a good job with his farewell scene with Shmi. I also thought his introduction to the Jedi Council was decent as well. Lucas at least set up that rocky relationship that came to a head in Revenge of the Sith.
To me, the prequels didn't need kid characters or kid-directed 'humor', not for the story the prequels were telling. The prequels needed to have the tone of Rogue One or the LOTR films.
Unlike many I didn't have a problem with Hayden Christensen for Anakin. He didn't get the best dialogue or writing to work with, but I thought Christensen knew how to go dark pretty well. I also enjoyed his scene with Shmi as well. And his turn to Vader. His love affair with Padme wasn't the most convincing, but I blame Lucas for that. He set that on a weak foundation in The Phantom Menace and it never really worked since that point. I wish Christensen had been chosen from the start. And that either Anakin had started Episode I as a teen or adult.
The scenes with Anakin marching on the Jedi Temple and the younglings. When he's on Mustafar and turns slowly to the camera with the yellow Sith eyes. And how he cuts down the Separatist leaders. I thought he handled that well. And his interactions with Obi-Wan during The Duel, though I thought that epic fight went on too long.
But, I also agree with the writing being poor, and not giving a solid foundation for the character to really grow in to the tragic character. It feels very sporadic in terms of character development. The love story was uneven, and had mixed moments that never felt like it fully matured in a believable way.
Overall, Anakin's performance had some great moments, but was lacking overall realism, and reliability in his motivations.