Nik and I have successfully kept a couple of plants alive for the past few years and we have recently begun to buy a few more. She has been telling me for years that she would like to have more plants and I am finally starting to realize how much of an improvement they are to our space.
The air is noticeably richer, in my opinion. (I realize most people would argue that there is no actual noticeable difference in the air, but I would at least point out that I feel happier having more plants in the apartment, so that is what matters!) We have a few that are meant to be air purifiers. They add so much color and life to our home as well.
We have a few others that aren't pictured. I have seen pictures of some apartments that look like miniature jungles, with several plants. I doubt that we will get anywhere close to that level, but we certainly look forward to making a few additions to what we have.