The open world aspect of the game is pretty bad and adds nothing, but fortunately it's not intrusive for the most part. The open world is just really barren without much you could do in it besides snaking past guard posts, but for the most part you can drop near the mission area. Traversal is also not bad, especially once you get D(rift)-Walker.
I like the game a lot just for the depth it offers. It's pretty much like MGS3 with how you can approach situations in any way you like but they kicked it up a notch here. Honestly the best mechanics in the whole series with how satisfying and rewarding it is. Enemies also can actually adapt to your strategies so there's another added layer of depth there. (Like if you headshot with the tranq a lot, they start to wear helmets all the time, which happened to me lmao) Too bad game seems unfinished overall, though.