The IST airport hotel is fine if a little clinical and functional. It is better than spending the nice in a lounge with a proper bed, shower and bath. Also a restaurant for breakfast and other meals. Cannot remember if they do room service. Its not very busy from recollection

The hotel is is two parts - one airside and one landside and is part the terminal itself. If landside, one has to walk outside the terminal right along the side and down the hill to access the hotel - found it a little confusing my first time there.

Just remember that if you are a UK or US passport holder, you have to pay for a visa on arrival at a separate desk before heading to immigration if you have to go landside.