Hmmm...we had a thread on this going awhile back. Too bad the search function is currently disabled or I'd find the URL for ya.
I think there are *few* areas I would avoid - obviously downtown Harrisburg has some dicey areas but that would be a longer drive than you would care to take anyway. The school should send you a packet with lots of pamphlets on apartment complexes in the area.
Many students live at Briarcrest which is across the street from campus - I find it a little spartan and some of the older units have 60s-era appliances. Not for me.
Hershey Heights is the newest apartment complex in Hershey - about 2 miles down the road from campus. Quite nice but unless you were sharing it would be a bit pricey; they are pretty stringent on their credit checks, income requirements etc, so I'm not sure if a lot of students live there.
There are several apartment complexes in and around Harrisburg. While my mailing address is Harrisburg. I'm only 7 miles from the hospital and it takes about 12 mins to get here. Many residents live in my complex (I'll discuss the name of the complex in a private message if you wish), although it is considered on the pricier end as well.
Ask the medical school if they can provide you with an Apartment Guide. Its a free magazine with lots of ads for local rentals, published monthly. I'm sure it would be a big help.