Pros:
It's fairly quiet, convenient to the subway, has parking spots (for a monthly fee, and only if/when available), has central a/c and heat, good light coming from large windows, some units have balconies, trash room on every floor, elevator. Pets allowed. Storage available in the basement (for a fee).
Cons:
The building is 10+ years old and appliances and things are beginning to break and aren't as nice anymore. The building wasn't insulated properly when built and so the large windows let in a lot of cold air in the winter, making it very cold near the windows (and expensive to heat/cool depending on the season). Very little bathroom ventilation, so mold grows quickly. Can frequently smell cooking/smoke, etc. from other units via the central air system. The building has a theft problem (packages are stolen frequently). The owners are slow to fix things and drag their feet if it's an expensive fix (we have things that have needed to be repaired for years and they don't want to fix it). Neighbors are hit or miss, we've had issues with noise, parties, and folks who don't clean up after their pets. The elevator is out of service for a few days at least 2-3x per year. The people they send to do repairs often do a half-assed job.
Advice to owner:
Be more attentive to the condition of the building and more proactive about maintenance. Schedule more frequent (and thorough) cleanings of all floors/trash rooms, etc. Build a trash enclosure for the garbage area in the garage (it's unsanitary). Invest in a better security system and virtual doorman for the building.