I also live in a 1 bedroom apt.. It's just me and my boxer living in 685 sq ft and we do just fine. In some ways, apartment life has been good for him. When it's nice out, my back door stays open and he is able to lay on the porch and watch the world go by and get his sunbathing in. He has a lot of friends (kids) that come over to say "Hi" to him on the porch. He gets at least 3 walks a day when I'm home, and we stop and visit along the way. He has a great social life and has not had a hard time adjusting.
The only problem I have is that he has separation anxiety, really bad. Luckily, I am able to bring him over to my sister's house everyday on my way to work. She has a boxer, and they keep each other company. If I need to just run out to the grocery, I leave him with my neighbor who also has a boxer, and he does great. Otherwise, as long as the weather is descent, he comes with me. I'm really lucky to have my sister, and my neighbor.