the thinking/thought process involved which i did not see even near equaled in any other field; so much in other rotations i thought became very algorithmic and mundane vs on medicine i feel you are always thinking, and asking why.
going along with above, the integration with the basic sciences you see in internal medicine. i was one who loved 2nd year of med school and felt like that information was all applicable to medicine.
not just having a high tolerance for rounding, but actually really liking it. liking the discussion of patients and disease processes and science and EBM! I like EBM very much and love its application to general medicine. plus, a love the process of generating a THOUGHTFUL differential diagnosis - not just spitting out any disorder this presentation could possibly be like i saw on other rotations but thinking up thoughtful active alternatives, etc. just overall love the cerebral aspect of medicine and to me being a "real doctor" in the truest sense of the word, in my opinion.
variety, patients (even CHFers and r/o MIs), working in the ICU, a tiny handful of procedures (not a fan), the interaction with patients families, and above and beyond the possibility for fellowship as i have a definite fellowship plans. i am pretty sure i couldn't do hospitalist work for a lifetime, or be in a general medicine clinic for a lifetime either but i definitely feel like it will be an incredible 3 years of learning!