i have advertised previously with them i never had any problems, the only reason i don't use them know is because my apartment rents its self with my website, but they was good when some of my guests used them

Yes we have, and been to several locations. Not had any problems yet. We also advertised on there for a while when we first bought our apartment, but now have enough returners so don't advertise anywhere but our website.
Just a thought, don't forget that it can also be quite nerve-racking for the villa/apartment owners, particularly if it is primarily their own holiday home like ours. There is always a worry that some guests won't look after it.

I have booked one through them for this May. Everything has gone very smoothly so far.

Booked Villa Dantella in Turunc through Holiday Lettings for Sept 2008, and everything was perfect!
Also booked a private apartment through Holiday Lettings and when we arrived it hadn't been cleaned from the previous occupiers, but not the fault of Holiday Lettings, a mix up with our arrival time, but this was quickly sorted.

We have used Holiday Lettings too and everything was fine, no problems and a lovely apartment.