This really is disappointing compared to the novels. Seriously disappointing. While I understand that you'd need to cut down a lot, the entire character of the series is different.
Haruka rather than simply being crazy, is madness personified. Or he's supposed to be. It doesn't come across.
His adventures are often hilarious, when the whole world is his straight man. Or they're supposed to be.
The classmate's are likeable and their reactions are entirely understandable. Or they are supposed to be.
I want to be glad to see this drawn... if it wasn't so very disappointing in contrast.
The novels are so much more satisfying in every way. Start there, and if you like read the adaption after. You might even like the manga anyhow, until you know what it should be.