Stayed in the busy summer period, but the Amalfi Resort was the right choice for us. Simple, but comfortable and clean villas with two excellent A/Cs, comfortable beds and well equipped kitchen. Pool and tennis courts were always busy, but worth using and kept in good condition. Internet connection wasn't always fast (often in the evening) but happy to have it.
No problems at all with neighbours, despite villas all close together. Was very quiet by 10pm and didn't feel overwhelming like caravan parks with people walking past your cabin all day.
We definitely made the right decision to stay in Busselton rather than Margaret River. Busselton beach has very clear water, beautiful white sand and even with the busy summer crowds, it never gets too busy on the beach.