I grew up in North Philadelphia, where Temple is located, and it is very dangerous. North Philadelphia has a very high crime rate. Washington Square West, Rittenhouse Square,Society Hill, and Olde City are nice places to live in Center City ( which is the main part of Philadelphia). Olde City and Society Hill are expensive, Rittenhouse Square is less expensive and Washington Square West is affordable.
Washington Square West is also known as the "Gayborhood" and it's clean and in a better part of the the city. However, there has been an increase in crime in that area. WSW is also near Chinatown which is near a shuttle stop that Temple runs.
All the neighborhoods I mentioned above are near the 2 main subway lines that Septa runs. So transportation shouldn't be a big issue.
Outside of Center City, Fistown is the near artsy area but only parts of Fishtown. All the real artists got kicked out of Olde City because of a rise in rental prices.
Also there is always Manayunk, which is outside Philadelphia, it has all the charm of Olde City but much cheaper. There is transportation there too, but Septa isn't that great because they do not run as frequently as people would like.
P.S There is this rental company named William Penn Realty Group (WPRG) that works in the neighborhoods I named above and are gears towards the younger crowd. They are HORRIBLE landlords and their buildings are easy to spot because it would be the run down building sandwiched between the beautiful brownstones. They advertise on Craigslist a lot so beware. I had major rodent, trash, and service problems with them. They also recieved a bad report card from U Penn Students.