We've been on 3 - so obviously we liked them!
The childcare has been great every time (I have a toddler and a pre-schooler), loads to do and lots of lovely qualified staff, air conditioned nursery area, kiddies pool with shaded area, outdoor toys...even my eldest - who is a bit shy and not a great mixer..absolutely loved it...he jumped off the jetty into the sea, balanced on surf boards and went for little trips in boats as well as all the usual arts and crafts, bucket and spade and singsong type activities.
For us as parents it was lovely to have some time alone or together when we could talk without a 'mummmmeeeeeee' breaking in, and dh loved the sailing and windsurfing..I did a course on dingy sailing and loved it (although I'm very bad at it - the rescue boats are fun to ride in ) and we took a yacht out for the day each time.
We have been to Farmess (now closed), Vounaki, Greece - very big rooms but on a steep hill and I was pg so a bit tiring, and Javelin, Turkey - we are wanting to go back here as the food was excellent, room was fine (tv with a kid's video on at about 7ish each night, turkish cartoon channel the rest of the time), staff were friendly but not '18-30ish' in-your-face, sailing was a bit hard as it is very windy there.
I've raved a bit haven't I! Eeek...... um..I recommend it.
We've been on two - one pre kids to Kephalonia (now closed) and one with an 18 mo to Lefkas. Childcare was great. Unlike Warner's Sunsail can take the children through the lunch break, so if you fancy going off somewhere for a day you can do it. They also have night time kids club now I think, so after kids tea they can watch videos and play some more if they're up for it. Galini in Lefkas was VERY steep - no go for buggies really - but the rooms were quite nice - all different shapes and variations. DD was around a corner from us in a cot in the living room, and our bedroom area was up a couple of steps. Food was okay - not exactly great, but plenty of it, and no problems. There isn't really a beach at Galini - more of a pebble strip. But the pools were good. As with all Ionian islands, there can be lots of wasps in July/August. We enjoyed our stay.