I have lived a couple of blocks from Herkimer and Kingston for about ten years. I am a 41-year-old white woman.
The two big apartment buildings on Kingston between Fulton and Herkimer often have noisy teenagers hanging out and yelling, and I think there were a couple of shootings (one kid died, he was not the intended target of the shooting) because of conflicts between the young people there. There are usually police officers keeping an eye out.
I think a parks department worker was assaulted (maybe raped) in the park between Herkimer and Atlantic. But that was big news, i.e., unusual. There are lots of people playing basketball there, kids playing at the playground, baseball games in the summer, etc. Sometimes people zoom their radio-controlled cars around the baseball diamonds which makes a really annoying and loud noise, but otherwise it's a pretty nice and well-used park.
Street noise can be pretty bad, especially during the summer, with people honking their horns and blasting their radios. You might also hear the LIRR on Atlantic, but they recently replaced the tracks and it's much quieter than it used to be. You also have the occasional party with people blasting music into the night, but I think you get that anywhere.
People, like anywhere, can be nice or mean to strangers. Usually when I say hello to people on the street, they say hello back. Just a couple of times in ten years I had racist epithets yelled at me. Otherwise, everyone is usually just minding their own business, often polite, sometimes friendly. The usual warnings apply (don't text on your iPhone as you walk, be aware of your surroundings, etc.). If I get off the subway at Kingston-Throop at midnight or 1 in the morning, there are usually enough other people getting off that I feel safe.
The new charter school on Atlantic and Kingston is nice, and I haven't really noticed the increase in teenagers except after school (when the Kingston-Throop station can be crowded).
I think the bodega on the corner of Fulton and Kingston (Charlie's?) is open 24 hours. You are literally steps from the C train at Kingston-Throop, and a short walk to the A express at Nostrand. There are lots of buses right there (B43 up Kingston or down Brooklyn, B25 east and west on Fulton, B44 up New York or down Nostrand, B65 east on Dean or west on Bergen, etc.).
The fruit stand on Fulton and Kingston is good, and the people working there are nice. A block west is Super Foodtown (great grocery store, it has everything), and south of that is a 24-hour 7-11. There's a Duane Reade next to the Super Foodtown, in Restoration Plaza (where there is also a theater, I never went there, and different offices and other stores).
There are lots of hair and nail salons, and 99-cent stores. Also, plenty of fast-food restaurants and wonderful Caribbean places. King's Pizza (Fulton and Brooklyn) is really good. Lots of restaurants deliver to the area (Udom Thai, Sushi Tatsu, Bombay Masala, and more). For a typical, greasy, Chinese restaurant I like Tak King, they have gotten much better in the last few years.
You are not far from Tompkins to the north (Common Grounds coffee shop, La Table Exquise French bakery--seriously ... try the chocolate tart, Peaches Hothouse restaurant--a friend visiting from the UK said brunch there was the best meal he had in NYC, and more) and just a little farther from Lewis to the north-east (Peaches restaurant, Saraghina pizza, neither of which I've been to, and more).
Since Starlite closed there aren't many bar options. Auggie's on Fulton is like another world (everyone was friendly when I went there, but I still did not feel very comfortable). Essence (on Atlantic a couple of blocks east) is nice (I never stayed very late there, I'm sure the vibe changes the later it gets). Applebees in Restoration Plaza has a bar with TVs to watch sports, and it's okay ... it's Applebees. Starlite was the best, and I miss it.
There are lots of new places on Nostrand around Pacific. A new sushi place, soon a new wine bar called No-Bar, I think. North of Fulton is a very nice coffee shop, Ms. Dahlia's. People rave about David's Brisket House, and I love the doubles at Trini Gul, both just north of Atlantic. MAD hardware store on Fulton has a lot of basic home-repair stuff and cheap housewares, and the people working there are nice.
There's so much more (nice realtor on Fulton who will notarize things ... "flea market" on Fulton and Brooklyn looks like it has mostly knock-off bags and sunglasses, I never explored it ... I think there's a farmer's market in the summer, a few blocks east ... Bushbaby coffee shop farther west ... Pacific Oasis, a new cafe with pastries on Pacific ... Apple Radio Cars is a quick car service ... T-cup on Throop north of Fulton--they didn't have their sea legs when I went after they first opened ... ), but you can discover the neighborhood yourself.
There are plenty of things I don't like about the area, including the noise, but there are lots of amenities (not everything, but plenty, you just have to look). To know if it's a good fit for you, you need to check it out, hang out during the day, walk around at night, etc., and see how you feel. Yes, there is crime, but there is everywhere. Just mind your own business, be respectful, and stay aware, and hopefully you will not be involved. To me, the majority of people are working families, lots of kids, just doing their best. If you move in, welcome to the neighborhood!