Its a magnificient opera house and you can just visit for pictures. But if you like opera (both modern and classc) you can have a wonderful performance. You can ask your hotel to give you the programme and they can book by telephone. Allo you have to do is to pick up the ticket before the show.
A few blocks walk from Jakominiplatz is the Graz Opers House.
The building was designed by renowned architechts Helmer and Fellner. Here tradition meets modernity. Alongside the Operahouse is a steel sculpture "Light Sword" initially caused controversy, but has since long become a symbol of the city's comopilitan attitude.