I think the cartoon style removes some of the seriousness from the app. It looks well-designed but I don't think I'd use it (maybe I'm not the target audience but who is?).
Given the massive amount of 'serious' stuff that they have to go through every day, we thought that a more 'fun' style would be easier on the mind (and on the eyes !).
After a day in the clinic (I am a practicing doctor), I feel like I have brain damage - and I just don't want to even think about a medical textbook or journal. But something less serious might sit better with my mind.