Absolutely amazing. Huge, huge rooms (MUCH bigger than we've seen in other comparable Greek hotels), incredible attention to detail, glorious private pools to watch the ferries and yachts come and go from, lovely big pool with floats and views too. Tremendous service, from turndown, water and ice-water face towels beside the pool, offers of face cream, insect repellent...
We (family of four, kids 7 and 10) *loved* the breakfast buffet; the main hotel restaurant menu for snack and meals was a bit limited (dishes cooked really well, but range of choices really didn't impress) but as a quick and easy option they worked and there are tavernas within 7-8 mins walk so no hardship.
We didn't really take in the Agalia's shared-ownership connection to the Erego beach bar (and the Pathos Lounge, though we didn't go there) til near the end of our stay - sadly, because the Erego was absolutely brilliant. Better menu, amazing vibe and location, and truly gorgeous pool with a beach right alongside also. If you're staying at Agalia take the time to walk down (<10 mins) to the Erego early in your trip!
The hotel has a number of cats/kittens living on the grounds as is common in Greece - I have to say this made my 7 year old's holiday... she spent every spare moment sitting with them quietly in spots around the grounds, concealing bits of her souvlaki to take back and share with them, etc. They were very cute.