While looking for hotels in Hydra, we had several options in our typical price range (60-80 euros), but we decided to splurge for the Angelica Hotel, which was 120/night with breakfast.

The room was clean and nice, but very overpriced for the off season. There were many places in the area offering rooms for 60/night, which was more reasonable.
The breakfast consisted of cold eggs and bacon, stale bread, and some yogurt and cereal. It was certainly not worth the 10 euros/person.

My biggest issue was the service. The staff member we worked with was cold, unfriendly, and unreasonable. One reason we thought it would be worth the splurge was for the outdoor jacuzzi, which is advertised on their website, because the weather was going to be mild and clear. However, when we arrived, we were told that the hot tub doesn't run during winter months. When we emailed them to book, we said we only wanted to book if the hot tub was in working order, but we received no reply from them-- we assumed this meant it was working. We asked for a reduction in price, but the hotel manager got very defensive and angry with us, and told us that he could do nothing for us.

We also pointed out that the wireless internet (also advertised on the website) didn't work in our room, either, and he told us that we were lying to him and he saw us use it. (We had our laptop open to do work, but couldn't access the internet.)

In short, the hotel did not offer what we expected, and while I understand things like that happen, I don't understand why we were treated so rudely. If I were you, I'd elect a place with a friendlier atmosphere while in Hydra.