medellin is a nice city to visit, unless your doing something stupid or go someplace where you should'nt be going too. as for the apartments, lots to rent in medellin, but be careful, a lot of people that i know complained about not getting what they paid for. terrible beds, no internet or working computer, lots of street noise ect. cant say too many good things about the girls there either.
same for the agencies there, you really got to read the " fine print" because they are only looking for your $$$$ and not your best interests. i would try san jose 1st and them medellin or some other place after.