The art's fine. the overall idea is fine, but that's it. The manga's too short to do anything interesting with the concept stretched over such a long timeline. It doesn't really explore the training or the possible changes to the world or the timeline his presence and alterations would have. This is like the rough draft of where you could go with an isekai in dragon ball. While there is a general story and idea, it's still not very interesting. If you're a big fan of Dragon Ball, you could still give this a try. It's not terrible, it's just very forgettable. Though I would sayit's below average for how bare bones it is even compared to most isekai.