The Mariner cottage was lovely! Absolutely spotless with everything we needed for a 3-night stay. We enjoyed the view from our little porch and the shared lanai was also comfortable. Definitely away from all the hustle and bustle of the major towns (it takes about 15-20 min to get to Pahoa and another 20 to Hilo). Jaecob does a lot to ensure a clean and comfy place!
One thing to note is that the cottage is pretty close to the other rental cottage, so if you're looking for complete seclusion this might not be the one. Another thing is that there is no cell signal (for Verizon, at least) but there's decent wi-fi at the cottage. Hawaii is also infested with coqui frogs that call all night long, so light sleepers beware (this is an island wide issue and not specific to the Mariner).