He's quite good. I have a rather large collection of his works.

You might do well to check out Waita Uziga, Horihone Saizou, Suehiro Maruo and Machino Henmaru if you like Kago Shintaro.

Oh, by the way...all the aforementioned manga-ka either work exclusively in eroguro or surrealist material. But since you like Kago Shintaro, it shouldn't be that much of a problem.