It is an interesting concept and I've been noticing lots of positive reviews from those who ran. It came at nearly the best time possible, also. Still climbing out of Thursday and Friday's deep freeze. I don't think I'd want to do it as a goal marathon but I actually considered doing it as a long run this year before realizing I'd be double booked if I signed up for it.
Rita, there are several good options. Based on first hand experience and reviews I've directly heard from those who have run them, Whistlestop, Green Bay, Paavo Nurmi (if you don't mind a challenging course and the likelihood of challenging weather), and Lakefront are all great options and I'm sure others are also quality events.