When I hear Takeshi Obata, Death Note comes to mind (I'd assume most of you would have the same thought).
I've read Death Note (I've watched the anime first), Bakuman (Manga then Anime then Manga again), All You Need is Kill (Movie first), Platina End (manga only). I've also watched Hikaru no Go but only knew it was Takeshi Obata's work when creating this post. I loved all of his works besides Platina End which I only liked. His new works hasn't reached the level of Death Note and Bakuman, unfortunately.
As much as I would like to say that it's all about the story, I'd say his art still has a big impact to the manga. His art elevates the story to a whole new level. I couldn't imagine Death Note drawn by another mangaka like Eyeshield 21's Yusuke Murata, or Kaiji's Nobuyuki Fukumoto to be the same masterpiece. The drawback is he needs a good partner, which fortunately he had with Tsugumi Ohba. Death Note and Bakuman were great, maybe even modern classics that would be relevant for years to come. On the other end, Platina End was a disappointment. The story was only fine but the art elevates the manga a bit to be likeable.
I don't know if it would actually work well, but it was interesting to imagine Obata's art being used on Nobuyuki Fukumoto's work. Imagine Light Yagami playing Restricted Rock, Paper, Scissors. That'd be epic.
He has a beautiful unique style where if you a random page of any of his works on the internet, you'd know it was his.
I hope he continues to make more works, and I'll be excited to read all of it.
Maybe I should read Hikaru no Go as well.
How come this game has over 1000 bugs (I'd imagine minor bugs?)