I've used them a few times, haven't been very impressed sadly. First time I'd booked someone to come on a bank holiday Saturday, the guy texted me the day before saying he couldn't come. I had people coming over that evening so had to do a rush job myself that morning.
Next time (so first time someone actually came out) was a young girl, she was brilliant the house was sparkling afterwards, but for her second time due she just never showed up. I texted her after about 30 minutes as I was waiting to go out and she asked could she come another day, no explanation.
Third time I got another lady, she seemed to fly through stuff while I was there, I left after about 30 mins and when I got back I don't think she had done much more (2 hour slot). There was actually a 'dent' on my double bed on the duvet where I think she had sat herself down for the rest of the time lol.
I haven't used them since, just don't feel like anyone I get is a) reliable and b) can do a better or at least match the standard of cleaning I can do if I get the time.
Pity as I will happily pay for someone to come regularly who is good and reliable. At the moment a girl comes every 2 weeks or so but I'm not sure she is doing what I'm asking her to (she was referred from a friend) so I'm still looking!