We really liked this place. The cabinas are spacious and clean with coffee makers, refrigerators, and a good, hot shower. Each room has an outside patio with comfy chairs to enjoy the AWESOME views of the volcano. The grounds are planted in LOTS of flowering shrubs and fruit trees that attract lots of hummingbirds and other wildlife.
On my previous trip to Arenal, I stayed at Lomas Del Volcan. It was new at the time, and pretty cheap. We stopped by this time, and their rates were well over $100 now (rainy season rates)! The funny thing is - Campo Verde is almost a mirror image (on about half the acreage) around the hotter side of the volcano - and for around $50 a night! The host spoke very little English, but she was very nice, and we all muddled through. I would definitely recommend this place!
One word about the "rainy season". I noticed some people complaining about the volcano being clouded over in the dry season. Let's face it, weather is always a crap-shoot. This was my second trip to CR in the so-called "rainy season" and we had plenty of sunny days, both trips, even at the volcano! Now, I'm from Florida, so I'm used to afternoon rain in the summer - but still - considering the discounts during the rainy season, I think it's worth it. We were in CR and Nica for almost 3 weeks and never had a single day where it rained the entire day, or ruined our plans.
By the way, as far as the 'green side' versus the 'hot side' of the volcano. You are probably more likely to get a clear sunrise on the south and east (green side) of the volcano, because it's less likely to be rainy/cloudy in the morning. But if you get lucky and get a clear sunset on the rocky north/western side, it looks like this (see my pic).