Depending on what matters to people, road races are a great deal, most are ~$50. For me, I love to participate in a legit competition even though I am over 50 years old. Sometimes I pick a dud, but the ones I have repeated like Boston, Falmouth or Cherry Blossom, have so much appeal between the course, competition, excitement before during and after the race. It is always just a great time for a runner to visit those towns. Same is true for NY.
$300 relative to other races is not as great a deal, but NYC is one of those special races if you enjoy these big competitions. It is an exceptionally long day but the course is insanely scenic, First Ave. is a unique experience as is Central Park to the finish. Weather is usually favorable. Do it with friends and find a great place to meet after, it will be memorable. If you don't particularly like NYC or massive crowds, don't do it.