Should be a great place to stay. The rooms are lovely and new and clean. The breakfast is very well done and worth the 10 euros even though it is optional which is annoyingly rare in Greece.
The problems I had were partly my own and partly theirs. The first night I was there, I slipped and fell in the tiny little stepped shower stall and smashed through the tiling surrounding the stall, cutting open my shoulder. That could be seen as my problem alone but the stall was so cramped and the tub seat or step so rounded that I'd be surprised if it didn't happen to other weary travellers with some regularity. But tiny is the general theme for Hotel Katherine. The rooms weren't Tokyo hotelesque in size but I'd never been in smaller ones. So who cares? The rooms are small. Not a big deal. Except when there are bugs. The third night I was there, my wife joined me and we got a much larger (relatively) room where I encountered three distinct species of arthropods. One was ants. Hundreds of adventurous little red ones. "Meermeengi" in Greek. You'll need to know this word when you are complaining about them unless, as I did, you captured a sample of them in that little bag they put the glasses in for the room. The other two I did not know. One of them joined the ants in the bag and the other was too darn fast for me but I would describe as akin to the earwig in shape, size, and demeanor. This was my entomological activity at three in the morning when we returned from visiting friends. I didn't want to change rooms even though, in fairness, they did offer when I explained the situation. That morning, I approached the manager and proffered the crawling little beasties in the baggie. I asked if he would do anything about the situation. He asked what I had in mind. I suggested he refund my money but he said that I had used the room. I explained that the insects had also used the room but maybe he would have better luck in getting money out of them than I had. Unfortunately, I got stuck with the whole bill.
I had to tell my story but ultimately, it is a decent place in a convenient area. Bargain them down from whatever price they're asking and don't pay more than 75 euros with breakfast in high season for a double. Make sure you take a taxi there after midnight.
