Stayed at Tabacon for 3 nights the week before Christmas. The hotel was very nice as expected though it turns out that most rooms do not have a volcano view except the upper floor in the 300 building.
It is a short walk down hill to the hot springs which we tremendously enjoyed during our stay. If you don't want to walk, the hotel shuttle comes about every 5 minutes so no big deal. The springs are about the closest thing I could imagine to the Garden of Eden. Sitting under a 100 degree natural waterfall felt great and the grounds are simply beautiful with many quiet areas to relax.
The food at the hot springs restaurant was excellent for lunch as well as the dinner buffet and price was reasonable for a hotel restaurant.
My son and I were thinking about doing a local mountain bike tour for $90/pp but then found out that the hotel as it's own decent bikes that you can use for free. We took a nice though hilly ride down to the lake and around an off-road loop that was scenic and a great workout but you need to be in decent shape.
Overall, we were very satisfied as the hotel was fine, service excellent and the hot springs which we visited twice every day were amazing. Would definitely stay there again if coming back to Arenal area.