I've been advertising holiday rentals with OwnersRentals.com for over 6 years now, as a property manager i have to look for the best deal and service, and have always found them the best in both. I also contact the owners before adding their property with OwnersRentals.com and always get a very positive response.(To be honest they usually ask me first to use ownersrentals)
I have personally used them and i also know of lots of people who have used them to book holiday rentals with them as well, all with good reviews.
I would highly recommend them to anyone want to either advertise a holiday home or book a holiday rentals with them, based on my experience.