I am a part time freelance writer and have worked for a number of different "content farms" and crowd sourcing companies, and Textbroker is one of the better sites I've found. They have a lot of work available; their pay scale is decent, and their customer support is excellent. My only issues have been that some clients try to scam authors out of content by requesting revision after revision, and in those cases (I have only experienced two) TB has been unwilling to intervene on my behalf.
Textbroker is not the highest paying site around, for sure. Their four star writers get 1.5 cents per word (they charge clients a fee as well, so the client pays more than that.) However, if you write solid, well-researched, ORIGINAL content, you will get paid what you are owed. They use PayPal, and I have never had a problem getting a payout; it is usually in my account the next day. In fact, my only problems have been with clients giving poor instructions and then complaining that an article didn't meet their needs. However, now that I know that TB gives me the ability to look up a client's "stats"--the percentage of articles they have rejected or requested revisions on--I avoid that issue by checking to make sure the clients I'm writing for don't have a high rejection or revision request rate. (The client I had a problem with had a rejection rate of over 50% and a revision rate of close to 200%.)
As to the complaints by clients that the work is substandard--they are probably right about 60% of the time, but what do you expect for < 2 cents a word? What's more, I find it astonishing that these people think that the writers should not only write well, but also know about SEO algorithms, keyword density etc. That is the CLIENT'S job. American companies have gotten so used to sending everything overseas that they seem to have lost sight of the fact that they are not going to get the same amount of work from an English speaking worker in the USA as they get from someone in India or another impoverished country for $4.00 a day.