Despite being located in a party town, this condo is quiet and peaceful, and the GOOD air conditioning is a lifesaver! Some places are designed to be looked at but not touched, but this condo is nice looking, functional and in good working order. And it's an easy walk to the center of town (on the road OR on the beach -- take your pick), and the ocean right behind the condo. There's a cute pool that we swam in several times and somehow had all to ourselves each time. This may be different during high season, but when we were there this was the case. The owner was very helpful and she was a pleasure to speak with.
Our favorite restaurant in Jaco is a place called the Green Room -- it's not very expensive and has an interesting and varied menu. We went there three times: once for a frozen fruit drink and twice for lunch. Next time we want to try their breakfast!
As far as activities, we went on a cliff-rappelling + zip-lining adventure which was excellent. And our trip down to Manuel Antonio National Park was breathtaking: we saw sloths, two kinds of monkeys, parrots and all sorts of other amazing animals.
We can't wait to return!