Maritime Race Weekend is a well organized and fun event. It's held on a scenic course in a quaint coastal community, but is still close to the City of Halifax. I particularly like that it is close to my home and held on roads that I train on, but I think that visitors from away would also enjoy this race. For those who like a challenge, you can choose to run a 5K the evening before the marathon. The shirts and medals are great.
The course has a few hills, but I would consider it mostly flat. The toughest hill is about 3K in and you get to come back down it near the end of the race. The first and last 3 klms are along Halifax Harbour and very flat. There is also about 7 klms of very flat rail trail from klms 23 to 30. You should be able to run this course at a nice even pace.