We stayed for a week in January and had a great time.
First, the animals. We saw spider monkeys, capuchin monkeys, macaws, coatimundi, blue morph butterflies, jesus christ lizards and green parrots. These were just in the back yard of the house! We also saw squirrel monkeys, howler monkeys, (which we heard every morning) a sloth, iguanas, and many types of hawks and falcons on short walks down the road. We hiked up to the waterfalls one day where we also found several poison dart frogs. This is really a great place to just take it easy and enjoy nature.
The house was pretty much exactly what we expected from the descriptions given. No issues at all for us. The only thing I wish there had been 2 kayaks instead of just 1, so we could have gone for longer rides.
We ate at Martinas several times, good food, you'll pass it just before you turn off the main road just a short distance from the house. We really enjoyed the farmers market on Friday afternoon. I bought some fresh tuna to take back to the house to cook, it was delicious. I got some handmade wood bowls that were awsome also.
The roads definately call for a 4WD vehicle. Nothing extreme, just lots of rocks (smooth) and a couple stream crossings. I would also make sure you bring a flashlight for each person in your party. Bugs came out at night, so we'd get inside the mosquito netting covering the bed and play games.
I didn't get to do any surfing on this trip, but our neighbors went out every day. They said the surf beach was about a mile away and had some really long breaks they could ride forever.
Overall, I wouldn't hesitate staying here again if we ever make it back down to Costa Rica.