Back in the day Mamoun had the best falafel in the city. That was when Mamoun himself was there. Over the years, they got very popular, and eventually opened more locations ( there's one in Hoboken now too)
The pita got smaller , therefore holding less falafel and salad. The sandwich I had yesterday at the St. Marks location was horrible. The salad was good and seemed fresh but the falafel balls were reheated and burnt.
For a place that was so good, it seems like they just don't care anymore.
Other places have opened with far better falafel. i.e. Nish Nush, Ba'Al, Taim etc
Mamoun;s survives on its name I think,