I've sat in section 102 twice in the past. These are the perfect seats to purchase if you want to avoid sitting in the sun for a hot day game or for an overcast game where it could potentially rain. The overhang from the Pepsi Porch above will give fans in 102 plenty of shade, especially in the back rows. Our seats were affordable but not cheap; roughly about $50 a piece. You pay for the experience, not the seat, that's how I look at it.
The legroom is standard. Not too much room but you also won't be uncomfortable. Every seat has it's own drink holder too. These are not bleacher seats and there are no bleacher sectionss at all at Citi Field like there are at Yankee Stadium and Citizens Bank Park.
I've only sat in this area twice but watch the Mets every night on tv. Home run balls will reach these seats frequently but even with the fences moved in, Citi Field is still very much a pitcher's ballpark where plenty of "small ball" is put into strategy.
We had quick access to the food in the concourse. All of the best selections are in center field in the 'FanFest' area. 'Big Apple Brews' has an incredible beer selection and Blue smoke and the Shake Shack are the two most popular stands at Citi Field. If you're looking for a great Italian sausage, check out "Sausage Premio", a stand just outside of this section. Bring plenty of cash, a lot of the kiosks don't accept credit cards.