This was our first visit to Junquillal, although we had been to Guanacaste several times. We were there in early December, and enjoyed great weather most days. We had the pool to ourselves most days (except for the howlers, the lagartos and the birds), and also had Playa Blanca to ourselves except for the occasional fistherman.
Michael and Viki's villa is spacious, and the balcony off the master bedroom has views of both the sunrise and the sunset. There is a security guard/handyman on duty 24/7, and each of them was very helpful and seemed happy to assist with anything that came up. They keep the pool very clean, and will turn on the waterfall on request.
We can't really comment on the Hotel Iguanazul, as it turned out to be closed for renovations during our stay. If you are counting on access to its facilities (about a five minute walk) you might want to consult the hotel before your visit. However we discovered a number of other good options for restaurants and wifi elsewhere in Junquillal. Mundo Milo and Guacamaya were the best we found, although Cafe Surf, Lochitos, and Los Amigos were all good as well. The supermercado next to Cafe Surf was surprisingly well stocked.
The best excursion we had was the mangrove estuary kayak tour, $30/person, arrange through Sylvia at Castilo Divertido. We had also hoped to see turtles nesting, but that didn't work out while we were there. But a visit to the volunteers working at the turtle station near the beach is very informative.