ive worked for agencies for the last 3 years. i like the variety of work you get, and meeting new people ect, but it can be annoying when your all over the place. ive been very lucky, in that ive only been out of work for a week due to no jobs. ive been on some reasonable contracts, earbing some good money, but also been on some rubbish ones, ie: shopfitting, for rubbish monmey, and being worked like a dog.
ive had problems with one agency not paying me on time, but on the whole ive been lucky.
as for the agency taking some of your rate, ive got it on good authority, that the large agency ive been working through for the last year, only charge 5% of our rate on top. by doing this, they increase their market share, and increase profits.