Hi, we went with our two year old to sani beach resort in halikidiki this summer. We stayed at the beach hotel which was lovely.
The whole resort is very "manicured" which can be a bit sterile and its definitely not like visiting Greece, you could be anywhere. I've heard it referred to as "boden by sea" which sums it up quite well.
It really wasn't the sort of holiday we would have chosen generally since we tend to prefer self catering but I was six months pregnant and just wanted to relax. The nursery was fab. We put our son in a couple of days and he loved it. They also do babysitting too.
The buffet restaurant was nice enough, and the "eat around" program meant you could eat at the restaurants around the resort instead.
Can't comment on entertainment. Not really my cup of tea so we didn't see any of it.
V child friendly but that's also a small negative since on the one night we attempted to have a child free night, there were hyper children running around everywhere being ignored by their parents which was but annoying.
Overall though, is definitely recommend it.