My family of three enjoyed three nights here and would recommend this spot to many people. That said, there are some downsides that folks should be aware of. First, the positives!

-There are things to do for just about everyone. For example, our adventurous 8 year old loved the river tubing, but the adults and teenagers on the trip all seemed to have a blast as well.
-The rates are affordable
-The "resort" is sprawling in a way that I didn't comprehend ahead of time. Think the size of Yosemite Valley (not the whole park though) and you're close to the right scale. So there are less traveled/peaceful trails, waterfalls, etc. that you can explore.
-The accommodations are lovely, the water is hot (solar panels on the roofs), the beds are comfy, everything feels safe etc.
-The food is both good and very affordable. We were pleasantly surprised by this given that you really have no choice but to eat at the resort, so they could charge more for less quality.
-The resort is soooo close to the airport. We visited on the tail end of a 6 week trip to CR, so being able to wake up on our last morning and drive to Liberia in under an hour was great. This leads me to the negatives...

-You're close to the airport, and to other popular tourist areas, so you will likely encounter large busloads of tour groups. In our case, there were two different massive groups of high schoolers staying at the resort, and they made their presence known both around the main grounds and whenever they descended upon one of the main areas to visit. The resort doesn't seem to track/cap how many buses can be at any of the attractions, so you may--like we did--find your lovely, peaceful soak in a thermal pool or waterfall immediately ruined by dozens of loud people all at once. We've never encountered this at other, perhaps less accessible regions of CR.

-Some of the tours seem more Costa Rica "ish" or Costa Rica "light" compared to the more natural/rugged destinations in the rest of the country. This could be a good thing if you're new to CR or to adventure travel, or if you're traveling with multiple generations. For us, it was a little lame at times. Your mileage may vary.

-There is no way to re-heat food in your room, and the fridge is tiny/full of mini bar items. As I mentioned, you will be eating all of your meals at the resort, and they'll give you to-go boxes. But it's hardly worthwhile unless it's small and you want to eat it cold later. The result is that there must be a huge amount of food waste, which is troubling from an environmental standpoint and annoying/expensive from a guest's standpoint. We would have loved to warm up the previous night's dinner for lunch the next day in between adventures, but alas...

Hope this is helpful...Pura Vida!