*Spoilers* I found it really boring until we got to the final confrontation between Yuya, Sora, and Yuto (episode 35, I'm pretty sure). The four dimensions were really intriguing and that actually got me addicted to this show.
This show has its ups and downs. The little "dueltaining" aspect was completely unnecessary and didn't really make sense. Actions cards are stupid, it basically proves how unskilled Yuya is compared to the other previous protagonists like Yusei and Judai. There were a lot of unnecessary elements and stupid arcs (cough cough, Battle Beast arc). It also came with a lot of disappointments, like there was even character development for some people.
Yuto's "death" was really dumb, and was probably one of my greatest disappoints ever. Yuto is probably my favorite character in the whole series and he was only alive for 18 episodes, they should've expanded on his character a lot more. I also found it really weird that we had absolutely no interaction between Yuya and Yugo (excluding berserk Yugo and Yuya's last duel with Jack).
The appearance of the legacy characters, Kaito from Zexal, Crow and Jack from 5D's, Edo and Alexis from GX, was really amazing additions. The fact that Yuya became (although not on purpose) the final antagonist of the series was a huge shocker and that really took the cake. Although, I did find the 1v2 duels a bit absurd especially with how broken Supreme King Zarc's effects were. In the end, this show is worth the watch, it's super nostalgic and amazing, we even get New Domino City from 5D's and Heartland City from Zexal and Duel Academy from GX.