i did medicine first (followed by surgery and then peds) and, while i think it is more difficult (at least here) to honor medicine early in the year, i definitely think i'm having a much easier time as the year winds down.
it's more difficult to honor because it's a very demanding service and you're absolutely clueless about everything...how to write notes, how to present, everything. heck, the first time my pager went off, i looked around for 30 seconds before i figured out what it was. in fact, one attending told me that he rarely, if ever, gives honors in the first month solely because it's the first month. BUT, i also had no concept of what clinical medicine would be like from a JMS standpoint, so working my ass off was my norm. then, when i got to psych (9-4, no call, no weekends) i felt like i was working part time and my classmates that were doing medicine had a cruel reality check.
another potential downside is that your interns will be new and have less time to spend teaching you since they'll be struggling themselves. i found this to be somewhat advantageous, though, because they were so swamped that my pts really were my pts and i was expected (or maybe required) to be responsible for all aspects of their care with direct guidance from the senior resident (read: more experienced, better at teaching, more responsible for your grade). though frustrating at first, it ended up being great because we really felt like we were making a difference (ie. if we didn't call the consult, bug radiology, talk to the pathologists, etc the stuff didn't get done) and we learned not only a ton about medicine but also about what we were capable of when pushed harder than we wanted to be.
overall, i think medicine is a great first rotation. it encompasses nearly everything in some way and you should learn how to perform/document a complete H&P, how to present concisely, and, most importantly, how to approach complex pts systematically--all of which will help you regardless of what you end up doing. this is especially true since you're currently not considering medicine as a career, so you'll get "broken in" before you do the rotations in which you'll really need to shine.
hope this was helpful without being too long-winded. i certainly wouldn't worry about this if i were you. good luck and please post other ?s as they pop up.
peace.