AJ113, I am sure it works well when it works, otherwise it would have gone down the tubes by now, but try as i might over many months, I still couldn't sort out the log-in errors and neither could they. Can't deal with people like that I'm afraid.
EricaandJohn, sorry not to have been there for you; I'm surprised our listing is still there, although I guess it's in their interests to keep it there (along with many others I expect) as it looks better for them to have as many listings as possible.
rgawith, no experience of ruralbulgaria.com I'm sorry: our apt is at the seaside, so wouldn't be appropriate. Our main customers these days aren't Brits at all, which probably accounts for why the holidaylets.net site has been so useless.
My general view is that if an ad website is free it's not worth the effort; they just want you to boost their listings before selling the site to someone else at an inflated price. Maybe.
Nor does it follow that spending a fortune on ads will bring in the bookings: we did a year on holidaylettings.co.uk and didn't get one booking out of the dozens of enquiries we got.
Try doing a Google search using a phrase that you think your kind of customers would search with, and see which sites come out in the top three.