Nils was a very genial host! He was good at following up with us about check-in/check-out (though I'd recommend you beat him to the punch for manners' sake :) ).
The pad is cozy, but well furnished and stylish. Supplies in the kitchen are minimal, but sufficient--we made pancakes!
The neighborhood and location is great--it's so walkable. We walked back from the Blue Jackets game, to have breakfast (Tasi), to 16-Bit (excellent barcade), to Giant Eagle (grocery store), and there's a ton more to do in the area. It's also central, so easy to drive/Uber to other areas.
If you need perfect silence to sleep, you'll either need earplugs (which Nils provides) or to consider another spot, as you can hear cars driving by, but I wouldn't describe the place as loud.
There are heating units at floor level that get the job done, but can take a while to heat the place up (I went in mid-December).
The bed appears to be a full-size, so if you're a couple who needs space, it might be a little cozy, but we were totally comfortable. Also, you'll have to walk up two flights of stairs to the unit, so prepare for that.
Columbus is a great place to visit, and I enjoyed Nils' pad. I'd definitely consider staying there again.