Well I hunted northeast Maine very close to the the NB border (near Houlton, ME) and a friend of mine hunted across the way in NB. He hunts there every year. He usually does better than me getting a buck most years but neither of us scored this year. This year it seems rut sign and activity was scarce, as well as fresh tracks, etc.in both places.
He hunts a camp used to be Parsons, run by Lloyd Parsons who passed away a couple years ago but his son still accommodates their regulars that come and hunt unguided. I hunted with Parsons 25 years ago and there were decent deer numbers, but the place had a lot of camps and hunters back then, not so now, a lot of them closed up.
If you're a stand hunter I think NB is better suited to that due to the type of woods, but I understand they've done a lot of clear cutting in that particular area. I believe NB also allows bait piles, or at least they used to, but not sure about that now.
Whereas Maine IMO is more conducive to the still/stalk hunter who prefers to go after 'em on the ground with open sighted lever and pump guns, through thick woods and swamps (map and compass skills essential, take your chances with GPS). There aren't too many places where you can hang a stand and see for any distance in that area (Aroostook/Washington county)
I'm actually considering trying NB next year but we'll see. Both places harbor some monsters, but of course seeing one and getting him is another matter. Maybe someone else will weigh in.