As the "hanare" part of "hanareya" suggests, this location is quite far from what you might consider urban Japan, and as such is a good place for some relaxing quiet time.
The ryokan room I had was very spacious despite being the smallest type, especially for one person. There was the genkan (entrance area), a big room for eating, a big room for sleeping, a corridor with chairs/tables and a safety deposit box, a closet with a yukata, a toilet, a separate bathroom sink area, one small indoor onsen and one small outdoor onsen.
I ordered the half-board option, and requested to have my meals in my room. The way that worked was they'd deliver the trays to the entrance where I'd pick them up, then once I was done eating I'd call the front desk and they'd come and take back the trays. Food was nice.
Not much to do outside at night, I just walked to the MaxValu supermarket and back as a night stroll.
If you're coming to Kawazu for the cherry blossoms, maybe come towards the middle/end of the Kawazu Cherry Blossom Festival dates. I went basically the day before the festival started (not intentionally, timing just happened to be a near miss), and whilst this year the sakura were slower to bloom than usual due to the cold, I don't think you'll see much on festival day 1, just the occasional single bloom here or there.
It's inconvenient to get to (need car), but I'd recommend also checking out the Izu Orange Centre in the area and trying the orange juice there.
