Excellent! I had a standard version of that bike for years - GS650GT. Was my primary commuter for 6 years.
They have all the good and bad points of all the Suzuki GS series. Handle great and stone axe reliable but need to keep an eye on stators and voltage regulators.
If the pipes and intake are stock, they're jetted "EPA lean" and get great mileage.
That bike is 35 years old now. Check all the rubber - brake lines, fuel lines, etc.
Use good tires. Dunlop, Metzler, Avon. They cost a little more but are worth every penny.
Check out GS resources - more than everything you ever wanted to know about these bikes.
http://www.thegsresources.com/
Have fun. Be safe.