We had a wonderful stay in Palm Grove, the staff are wonderful and attentive, the location is great; there is a huge roof terrace where you can sit and just chill out; and the owners are lovely and always willing to help out. And all of this just a stones throw from Unawatuna Beach (about a 5 minute stroll).
The rooms themselves are basic, but they are very comfortable and clean, and to be honest, if you are spending time in your room, then you are not making the most of Sri Lanka. The breakfast is basic, mainly consisting of fruit and coffee, but it is also very nice.
If you are planning to visit Galle, then staying here would be far better than staying in the town itself.