Any city that has at least one Irish Pub can't be all bad: It's Molly Malone's and it's in the Historic District. Santiago is a busy University town. It has department stores (a large Corté Inglés), Discotecas (one called Saturday Nite?), restaurants and bars. It even has a Cafeteria that makes its own churros (no porras): Yate on c/Senra. It is very well communicated with regional rail (or bus) service to/from Vigo, Pontevedra and a'Corunha. For a student I think it is an ideal size city, much more 'manageable' than a larger city such as Madrid.
Once you get established with your fellow students, I think you'll have a 'ball.'
BTW
About 3 or 4 years ago, the Chieftains (Irish folk group) recorded a 'Santiago' CD featuring Carlos Nuñez (from Vigo) as their lead bagpiper (gaitero). Unfortunately, you missed this year's bagpipe competition. It usually takes place toward the end of May.