Not stayed there but passed it loads of times.
We stayed just up the road from them at Kalonisa last year.
Andreas does a smashing brekkie too by the way. Rita, his missis runs the car hire place attached Ritas CareHire) she is English and will help with anything you need to know.
They look fine and all rooms face the pool. There is however, I understand, another block next door which also belongs to them.
You could try
http://www.justkos.co.uk choose Kefalos and Apartments and you will find lots of reviews on there.
Also,
http://www.kos.me.uk/index.php?board=5.0 you can get lots of help on Kefalos there from us that have been loads
Good luck
Heather