Positives
Makkasan has been home to yself for almost 5 years now - It boasts access to MRT Phetchaburi as well as the airport link. You can quickly get to BTS Nana and BTS Asok via the MRT or a bike taxi for around 30thb. There are lots of local restaurants and bars - also regarding condos and aprtments in Bangkok the rates are pretty fair from mid range to luxury. It's a central area that gives easy access to the heart of Sukhumvit road and all that Bangkok has to offer! If you're travelling around Thailand on business a lot then the airport link is very handy as you can get to and from Suvarnabhumi Airport very easily - not having to worry about traffic when getting to the airport is a massive plus when on a tight schedule!
All round it's been a great place to live and I recommend it to anyone wanting options to access most areas of Bangkok conveniently. Good for socialising and for business.
Negatives
Being in the heart of the city means traffic gets crazy, as well as the pollution and noise that comes with this.
However if you're on high floors with decent windows/Air conditioning then you can ignore all of that at home and enjoy the views.
Also unlike other areas there aren't parks in the district itself really - you need to head to Lumpini Park or Benjakiti park to see some greenery - on a motorbike you can get access in 10-15 minutes however.