I booked my wife and I in for a 4 days over Christmas. It as a bit last minute and an not normally an eco lodge vacationer. Wow! Awesome spot, great rooms (though, be prepared to use the fans!), excellent food, and fantastic staff. It is a small, 9-10 unit place, with pool, dining, spa, yoga, surfing, paddle boarding, and the beach. The owners, Gary and Dee, met us and settled us into the place and launched us on a paddle board before having to head to Managua for Christmas with their kids. But, Sandro and the rest of the staff spoiled us. In fact, for most of our stay we were the only guests. It was our own private resort! Sandro is amazing. Attentive, yet not on top of you.
We had fantastic fun with Christmas Eve and Christmas day dinners (fresh surf and turf that was the best I have ever had) and live music. For our last 2 days, 2 other girls from our home town of TO arrived, along with a family from NYC. All were great, and we enjoyed some great discussions with them.
We mainly hung out, read our books, surfed (disastrously - big surf), walked the beach, went to neighbouring places for lunch, and ate and drank.
I would highly recommend a few days at Solost when in Nicaragua.