Jyvaskyla, situated in Western Finland, is the capital of the county of Middle Finland. With just under 130,000 people, Jyvaskyla (or Jyväskylä, as written with scandics) is both a university city and a major place for commerce and employment in Middle Finland. With a very long history (first signs of agriculture over 3500 years ago), Jyvaskyla was officially founded in the 16th century.
Served by it's own airport, Jyvaskyla is also a very central point in Finland's public transport system and such, the transport and hostel options are good. There is a comprehensive bus and train network. The internal public transport also works very well, and while the central city area is easily compact enough to walk, you might want to catch the bus from your Jyvaskyla hostel to see some of the outer suburbs.
The hostels in Jyvaskyla are in line with most hostels in Finland. The prices are reasonable for the quality but a bit on the expensive side.
Home to both the University of Jyvaskyla and the University of Applied Sciences, the city is home to large amounts and students. The nightlife and restaurants in the city central are very varied and the quality is really good.
If you come into the city in the wintertime, there are some special things you might want to do. Every winter there's a skating area in the nearby Jyvasjarvi (Lake Jyväs), which has a very nice atmosphere and is definitely worth visiting. In the summertime, there are many nice beaches to go to, and even if being so far in the north, the temperatures are often warm enough to enjoy a nice day on the beach. Your Jyvaskyla hostel should be able to suggest other activity ideas during your stay.