Yeah, you definitely have to take the reviews with a grain of salt. There are people who just plain cannot follow directions, and then ultimately get rejected, writing all 1 reviews. On the other hand there are also people giving 5's to requesters who pay for jobs that work out to $1.00 per hour.
But all in all I use it and won't work for someone who has consistent bad reviews. Also I won't work for jerks like that guy you described who said he's going to block you. He's too lazy or uninformed to set up and use qualifications, so instead he's putting your account at risk with a block.