I have used them and they are ok ... and very cheap - £1.25 for 18 x 12 is amazing - but be careful if you want true neutral tones - in B&W I've found they have a cast to them which I guess must be present in all their output, even if its not immediately visible.
I have recently become dissatisfied with the lab that I've been using and so tried 4 different labs sending them each a couple of test print to evaluate their output. My conclusion was that
One Vision Imaging delivered the greatest colour accuracy - not as cheap £7.05 for 18 x 12 but when I'm producing prints that people are paying for, its important that they look right