I recently (as in last 30 days) told them to go away and quit sending me work.  The reason for that is they never seemed to voluntarily pay me.  Literally I would start asking for payment after 30 days, and it would still be another 30-60 days until I got a check.  Every time I was ignored until they wanted something else done, or I got very aggressive about when I was going to get paid.  Not one time did they send a check without me asking at least three times about when I was going to get paid.  It wasn't even a lot of money, I just KNEW every time I had to go after them and I hated it.

Ironically they ended up sending their work to another client of mine who does pay me in a reasonable manner.  The client called and asked me why I quit working for them (which I relayed my experience) - and then they told me that at one point they had to threaten GDS to get paid (which is why I ended up doing their work).  I would recommend them to NO ONE.  Maybe they treat other people differently, but that was my experience in the 15 months I did work for them.  It just wasn't worth my time, energy, and sanity.