The good thing about Chickpea is that the ingredients are fresh, and everything has a good clean taste. Price is good & decent seating, though it doesn't have the best feng shui... but that's how it is in NY, so they can hardly be blamed.
But it has weaknesses too, depending on what you're looking for. If you have a notion in your head of what a good falafel tastes like, Chickpea might not fit the bill. While the good clean taste might be preferable to many a palate, I personally find it a little too zingy (fresh) and too salty (which also accentuates this taste). The chicken shwarma is similarly clean, subtracted of the pungence of ethnicity, the richness of meat that has been hanging out in the store all day. I guess it's really a matter of taste: do you prefer white meat (more like Chickpea) or dark meat (more like other good falafel around town)? Are you uptown or down home? Not knocking Chickpea at all. It does well what it does. But people should know what it's does: it's a take on middle eastern food that fits into the "healthy" taste ethic we are in today (a natural fit).
But, personally, when I seek falafel, I'll look toward State Street near Brooklyn Heights, or Jerusalem Falafel on 104th & Broadway. Not as cleanly or yuppie, but you can't beat the taste.