Honesty while there are some weak points, I do think this arc overall worked. Personally I liked Kellan, as Annie said
"The Multiverse is full of people who do bad things for selfish reasons,...But the people who do good and expect nothing in return? I reckon they're worth protecting."
This why I liked Will and Rowan and why I like Ajani, Niko and other similar characters. As a biracial person I really felt Kellans story arc, while I did know my parents and raised in a mixed culture home, my father has passed and I do feel that loss of not being able to just ask him aspect of his side of the families culture.
I do think they need to figure out the balance of "main character/face", the gatewatch leaned a bit into stealing the spotlight while I felt we could have had Kellan more features and showing steps in his character arc during Ixalan. Ravnica was better overall, I do like how we saw him learn to fly I just wish that had been more tied to his own characters growth. I feel like there is a balance there that wotc can get with having recurring characters with Kellan doing a lot better as well being a singel character with a single arc vs the gatewatch each having their own arc that intermixes with other characters.
However the biggest thing positive I felt about this arc was how well it all felt tied together. While Kellan was the front and center character and arc we had Jace and Vraska doing stuff behind the scenes in parallel with Kellan. We had Eldraine introduce Kellan as well as being the first stop Jace as Ashiok made to recruit a person for the heist, Ixalan and Ravnica where steps along the way for Kellan while we saw Vraska reuniting with Breeches and Malcom and Jace learning Profts illusions skills and it all coming to a head in Outlaws. Really good way to let all these stories stand mostly on their own while connectign them all together into an overarching storyline. Makes me really excited to see how the next two arcs shake up and see how all these sets and storylines will ties together.