The light. We have tons of windows and high ceilings so it never feels small. Also, surprisingly, the amount of space. We moved into this apartment after 4 years in a 400 sq. ft. apartment, and felt like we were moving into a palace.
Biggest Challenge of Living in a Small Space:
The biggest challenge was problem solving for multipurpose spaces while operating on a low budget. The best solve we had was the IKEA hack we use to hold our books/TV/office all along one wall. We used the expedit series and left out some of the separating shelves to hold a stool for the computer, the printer, and the cable box, and used the doors/shelves to hide the clutter with some different knobs.
The other challenge was starting from scratch on a budget since we had to sell a lot of our old stuff because it was way too small (looked like doll furniture). All of the new big stuff, like the couch, was bought during our first Black Friday in the apartment. Most everything else was family stuff we had kept/Ebay/Craigslist/found on the street/used and collected throughout the year. There was one splurge item is the lamp next to the couch, which was a surprise holiday gift. My partner scored it on sale 4 months before Christmas.