We arrived to NY at 7 in the morning and couldn't check in our bags until 16 in the afternoon. That created a lot of trouble and extra cost for us. In a hotel you can always drop your bags before and after your stay and being a Airbnb host myself, I always let my guests drop their bags whenever they need to. You also have to check out at 10, but in a hotel it's usually 12.
Later I found out that you (at this time) could get a great hotel room in the middle of Manhattan, including breakfast, for just around 30 more dollars. Then you are exactly where you want to be and don't have to do do the travel back and forth. So to me, if airbnb is not much cheaper than a 3-4 star hotel, it's not much point to do airbnb unless you don't like hotels and prefer to stay in Brooklyn rather than Manhattan.