Disclaimer: I won my first stay at Hotel Castillo at last year's CRT Anniversary Party. The fact that the two-night stay was free in no way affects what is written below, for good or bad.
Fortunately, there's very little bad to report about the hotel. I was in room #9, the main suite. This living space includes a full kitchenette (which even features a blender for making foo-foo drinks). The dining/living space is large, with tall windows that admit a lot of daylight. The room is furnished with a big couch and a nice size TV.
The bedroom lacks windows to the outside, but has a window into the living area. This makes the room fairly bright during the day. The dressing room area and bathroom are spacious and very clean. While I didn't try it, the bathroom in #9 features a jacuzzi large enough to accomodate three adults. Very nice.
Downsides: If you're bothered by noise, the walls in the mansion section (old section) of the hotel are thin. Bring earplugs. The noise never bothered me, in fact I'd like to thank the three studs who were pleasuring their chicas around me. Nice lullabye...three different chicas having orgasms.

Another downside is that the desk will not exchange currency. I was able to break large colones bills into coin and small bills but was told that the desk doesn't exchange dollars for colones.
Another downside is that the bar, under new ownership/management never seemed to be open when I wanted a drink. I'm told that the restaurant should be open soon on a regular schedule.
Positives: The staff is very friendly and helpful. Marixa and her sister do a great job of keeping the rooms clean, Marta at the front desk is a champ, and Darren (manager) was friendly and full of helpful information.
Will I stay at the Castillo again. The answer is a qualified yes. I want to stay at a hotel which has an on-premises bar and restaurant. I will return to the Castillo when the bar/restaurant is operating on a regular schedule, but not before. Again, the bar/restaurant is not under Castillo's control, and I don't blame the hotel for having no food and beverage to offer aside from the tasty if simple breakfast.
For the money, especially with the cash discount... the Hotel Castillo may be the best bargain in barrio Amon at the time of this writing.
