Department store bikes are usable, but certainly not good quality bikes. The main problem is the assembly is horrible. You really have to go through everything and fiddle with it a lot since the compenents are not the highest quality, to make them work.

I also vote for good used. A Volvo with 200k miles that has been maintained is a much better car than a brand new Yugo. If you buy new crap, it will always be crap, never get better.