I recently spent some time working in Coney Island, home of the world famous Nathans hot dog. I'm not impressed with the place, it's quite dumpy. It's slated for refurbishment, and it needs it. It looks like there were once a lot of "pay by the hour" hotels there that have since been boarded up, isn't that quaint? Most of the shops are small and unwelcoming. For food there is Nathans (with limited seating), Popeye's and some other not too exciting fast food options. There are vacant lots that are overrun with weeds. I'm told by others that Coney Island at night isn't terribly safe in terms of crime. Have I convinced you to skip Coney Island yet??
The good? The subway station was redone and is and fairly nice for a NYC Subway station. Keyspan Park featuring the Brooklyn Cyclones is nice for a family baseball game. The amusements are classic old school types of stuff - wooden roller coaster and carnival games. The beach looks (I'm working there, not going to the beach) nice and fairly well kept up.
The verdict? Unless it's summertime or you really want a hot dog from the original Nathans, don't bother. If it's summer and you want a NYC beach or you want that hot dog, then it's not a bad place to visit for a couple hours during the day. But don't expect a nice fancy area, this is a run down little area with a beach and boardwalk. Nathan's hot dogs are pretty good too.