Three important things to know about this race. 1) its rather large... it attracts a lot of first-time half marathoners and groups of runners. 2) its 2 loops around the rolling hills of Central park and 3) there are also walkers.
The rest can pretty much be surmised from the above. The course offers several rolling hills which can be tough if you haven't trained for them, especially on the 2nd loop. Train for those hills! The larger crowds at the beginning and the walkers at the end tend to slow you down BUT the cheering crowds and happy teams of women help get you through. The positive vibe coupled with the accessibility make it a really exciting and fun race to run. And if you're lucky, April in NYC is beautiful.
The only minor let down was the expo. It not as awesome as I figured it would be! Tons of swag for purchase but not a lot of cool swag options for runners like you find at other expos. Bummer!