It's Perfect.
I haven't used it much and bought it since another kid in same Yocchen have it. From assebmbly point of view i think it's a bit tricky to assembly specially the brakes. I still couldn't get them work properly. It's really not easy to get everything right in perfect spot if you aren't technical. I usually work on my motorbike so i think i could assemble it but i find it very difficult to align the front brakes since they keep making noice while tyre is moving as it's touching with pads. So i think it's better to buy it from a shop so that they can assemble it for you.
I have bought it for my son as his Birthday gift and he's very excited to use it but unfortunately it's rainy season so we couldn't take it out on weekends yet.
Overall i feel that build quality is very good as it feel nice.