lets not ignore the fact that Sai is a master who have so much experience. Hikaru on the other hand only started a while ago. Even Akira started playing GO at a really young age and not just playing with amateurs but strong GO players. I don't really agree that the ending was just that but I think this really is not complete. Hikaru is still in the stage of progress. I think that Sai disappeared because he is not needed anymore and may have been gone to the next life or something. I think it was best that he left because if he stayed Hikaru will always depend on him. Now that he is starting to take over his life and be more mature. I think that in the near future he will be in the top just like Akira's dad. I think that Akira is there to motivate Hikaru's competitiveness and to do better in playing go. I think many will feel disappointed has many of us really expect Hikaru to be the best player. I am more disappointed that the author really made me so obsess with Sai and he decided to make him disappear so early in the story. I wish they could continue this manga and see if Hikaru became the top player along with Akira.

Wow, I was really reluctant about reading this after all the bad reviews about the ending, but.... Tbh, I feel like it just made no sense!?? ヽ(`Д´)ノ
(RAMBLING SPOILERS AHEAD !!)
To begin, it's just stupid to me that even though Sei's ENTIRE role in the story was to guide Hikaru, and there was suCH a difficulty on both their sides coming to terms with this, in the end it's literally meaningless. Yes, Hikaru is good at Go, but in the end he didn't show any true results. He just threw away all Sei ever thought him and scraped by his matches. It was so depressing.
I guess this is linked to the true meaning of owning "The Hand of God", which, based on the path Akira's Dad decided to follow (who was known to be the closest to The Hand of God), it was more based on veering away from the structured system of Go, where only winning and losing is important, and more towards truly valuing the game for what it is, and finding worthy opponents that make you want to give it your all (Like Akira did for Hikaru).
......Actually, in that context, I guess the ending makes more sense.
In a way, Hikaru did gain The Hand of God, because he was able to find games he enjoys with Akira, and gain acknowledgement for his strength, even beyond the systematized structure of Go.
But aside from that, I think there were a bit loose ends that I wish could have been tied properly. Like.... Did Hikaru & that other kid from the national team ever gain true acceptance for their career choices by their parents? What happened to that ginger kid that liked to cheat from the Go Club? Did he really ever really reform himself? Did Hikaru really ever reveal the truth about Sei to Akira? Is Akira really comfortable with the idea that Hikaru never really reached the level of Go play he had when they first met?
.....how long ago was this manga even published? Jesus Christ....I'm late for this wagon, but it's jut a bit sad that they didn't include just a lil extra to tie those tiny loose ends.....