I've stayed at Casa Tranquila twice over the years, and each time the stay has been perfect. Not only is Casa Tranquila itself flawlessly appointed and wonderfully located, but Donald and Nathan are such great hosts we've relied on them for concierge services on other visits to Manuel Antonio (including a recent trip where our group was too large for Casa Tranquila itself, but Donald and Nathan still helped us book tours and activities during our week in Costa Rica).
When staying at a vacation villa, two main factors can make or break the entire experience - the quality of the facility, and the attention paid by the owner/host. With Casa Tranquila, you can not ask for more from the villa itself, and your host. Donald and Nathan make it a point to greet you upon arrival, and make themselves available throughout your stay. You never have to worry about what you might find with other vacation rentals, where the owner lives remotely or out of the country and you're dealing with a property manager who services the villa you're staying at, along with countless others. With Casa Tranquila, you can tell the owner not only cares greatly about their own property and making sure it's absolutely perfect for every visitor, but also cares about your entire trip - every activity we booked through them was a blast (and booking through them means you get the best prices, and the activity providers take great care of you); every restaurant recommendation was spot-on; every tour or outing suggestion was perfect.
You really do get a good idea of what Casa Tranquila offers through photos and descriptions - the villa has amazing views, is wonderfully appointed, and truly is top-notch luxury. What you can't see in the photos, though, is the attention and care paid to you by Donald and Nathan during your stay. I'd not only highly recommend the villa, but also taking advantage of their concierge services to make sure you not only book the right activities while in the area, but get the best prices on them!