Can't tell much from the pic... General guidlines:
1. Bolt-on wheels? Usually found on cheapies
2. Frame material. If it's marked "hi-ten" steel or something similar, likewise. Better would be Cro-Mo (Chrome Molybedenum) Aluminum, etc.
3. Components. Better grade of Shimano bits, like Acera or better, generally indicate a better bike.
4. Are the other parts steel or aluminum? Steel stem, seatpost, hubs, etc. again indicate a cheapie.
Just because it's not a brand name that jumps out at you does not mean automatically that its junk; lots of small makers put their names on decent bikes. We have a Novarra that we found abandoned. Looks like a junker, but all LX components, Cro-Mo frame, etc. A decent-quality bike.