The Old Boathouse is on Portland Bill, right at the end. It's detached. The main thing is the view. You look straight out over the sea towards the lighthouse. You can sit on the decked patio and watch the boats go by. It's very quiet out here.
It sleeps four. Two bedrooms, one bathroom with a shower. It's got a 3 Star rating. It's clean and comfortable, not luxury. The stairs inside are a feature, I should say. They're the original spiral ones. They're steep and a bit narrow. You need to take care on them.
There's a pub about 100 yards away. They do food. The nearest shop is a couple of miles back in Easton, so you'll want to bring supplies. The beach at Chesil Cove is about two miles.
If you like walking, you're right on the South West Coast Path. You can walk for miles. The whole island is interesting for geology and history. Portland Castle is about a fifteen minute drive. Weymouth is twenty minutes by car for the harbour and a proper beach.
Within half an hour you can drive to Lulworth Cove and Durdle Door. Dorchester is about thirty minutes inland. The Jurassic Coast website has good information for trips.
Facilities wise: there's parking, WiFi, a washing machine, and a dishwasher. Bedding and towels are included. There's a BBQ. No pets.