I dont think it's a return to form at all. The campaign, while mechanically sound and fun to play, was otherwise quite unremarkable. The more open areas dont change that at all. I even think the game could have been better wizhout them, judging from the blast that was the first act.
But then the game might have turned into another Gears 4. I really dont think The Coalition are on the same level as Epic here and probably never will be with this series.
And then we have Uncharted 4, which not only refined its mechanics, but also delivered a very compelling story and experience. It was memorable and felt "whole". Gears has had cliffhangers twice now, stretching its thin story almost to the breaking point. In the good old 360 days you have fucked the Locust in the ass with every game. When they were over you always felt like you had done it, with only a slight teaser at the end to tell you the fight wasnt really over.
The longer I think about it, the more disappointed I am lol